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Journal of the Biological Society
Victoria University College
Wellington New Zealand
Although the freshwaters do not offer such exotic fauna as the seas, when properly established the freshwater aquarium is a valuable asset in the classroom and an object of beauty in the home. The variety of freshwater plants amenable to aquarium cultivation permits the setting-up of a permanent aquarium carrying many useful and attractive animals and plants. It facilitates the study of life-histories and demonstrates many important biological principles.
The common goldfish bowl—a bowl placed in the sun, with two fish but no gravel or plants—illustrates nearly every improper practice in tank management. Fed every day, the uneaten food and droppings from the fish are swirled up as the fish swim. Bacteria and protozoa bloom and cloud the water depleting it of oxygen, which in any case is in short supply because of the restricted surface area relative to the volume and the low solubility of the gas in warmed water. The fish gulp air at the surface. The water is changed, sometimes daily, to ‘keep it fresh’. A goldfish bowl proves one thing, goldfish are hardy creatures; but few other animals have this measure of hardiness and require instead the delicately adjusted environment of a ‘balanced’ tank. This is a tank so organised that the animals will enjoy as near stable an environment as possible. The equipment is a tank; clean water; a bottom of coarse sand or fine gravel; plants; animals; a cover; control of illumination; oxygen; and food. These items are combined with due regard to the influence of one factor on the other, to produce the ‘balanced’ tank, thus providing the highest measure of environmental stability which with experience can be adjusted to suit the need of one animal or another, or many.
All ‘balanced’ freshwater tanks are static. Aeration and circulation are not needed. The tank should be as large as possible. Ten gallons is a very small tank, twenty-five gallons a good size to start with. Shape is important. The width should be equal to, and the length double at least of the depth to provide a surface area adequate for oxygenation of the water. The frame should be sturdy and of metal with the bottom, sides and ends filled in with glass—never wood or metal. Slate and marble make an excellent but heavy base and ends. Wood waterlogs or warps, metal rusts unless painted and
Before filling a tank, take these steps: (1) Check the seal. The putty should be firmly and cleanly in contact with the glass, air-bubbles and other breaks can mean early leaks. (2) Select a permanent location for the tank since a tank must be emptied before moving, and this can throw a tank out of ‘balance’ for some days. Place the tank where no direct sunlight can strike it. If near a window, have one end towards the window. (It can be placed closer to the window in a south-facing room than in a north-facing room.) (3) Place the tank on a base which adequately supports the frame so that there is no torsion as the tank is filled.
Wash the tank out with water. Fill to an inch from the top preferably with clear pondwater but clear tapwater will do. Cover the tank with sheet glass to prevent loss of water by evaporation. Be patient. Leave the tank stand for two weeks to a month to ‘age’ the water.
Select material for the bottom of the tank with care. Soil, clay and similar material discolour the water or produce colloidal suspensions which will never settle. Obtain fine gravel or coarse sand with particles ranging in size from a pin-head to a match-head (white is more attractive than darker gravel or sand). Granules of this size permit debris and droppings from the animals to sink below the surface of the gravel where bacterial action is rapid, and do not clog the roots of the plants. Obtain enough to form a layer 1½ to 2 inches or more deep, and wash throughly with running water, stirring until the water runs away quite clean. Leave it stand several days covered with water, and wash again. Now added to the tank there should be little clouding and no discolouration. Spread evenly and then bank deeper towards the illuminated end of the tank and to the back, with a gentle slope to the front of the tank. If you plan to keep fish, make the bottom shelve to a wide, shallow, central hollow where uneaten food and faeces will collect and can be easily removed, or make a one inch deep groove for this purpose along the foot of the front glass.
Vallisneria is easily obtained, and a most useful plant. Wild plants are best from ponds, not running water; but ‘tank-hardened’ plants are preferable and can usually be purchased. Plant an inch from the glass, crowded at the illuminated end and scantier along the back of the tank so that the greater part of the tank will be shaded by plants from excess illumination. Spread the roots deeply so that the plant is secure, but do not cover the crown. Elodea, Myriophyllum, Cabomba, Sagittaria, Aponogeton, etc., can be planted sparsely in open spaces as ornamentals.
Lemna, can be used to control light entering through the top of the tank. Plants absorb oxygen twenty-four hours in the day, yield surplus oxygen during daylight but rob the water of this gas at night so that an adequate surface area is the only assurance of an oxygen supply for plants and animals alike.
Before stocking the tank, let it stand until clear, a matter of a week or more. This and the previous ‘aging’ period both give time for bacterial and protozoal blooms to take place. Such blooms cloud the water, often deplete the oxygen supply; but as they pass, leave the water crystal clear, as it will remain for even twenty years if the tank is properly managed.
In stocking a tank with animals, a step is taken which determines the type of tank management. The usual set-up is a tank containing animals such as small fish. The old rule, and still a good rule used with common sense, is one inch of fish to a gallon of water—no more than that, and
Alternatively, an aquarium can be stocked with minute animals which do not require feeding. This is the ideal tank for the classroom for it can contain protozoa of many kinds, Hydra, turbellarians and other aquatic worms, rotifers, Daphnia and other Cladocera, Ostracoda, Copepoda, Amphipoda, aquatic insects and aquatic insect larvae, the smaller aquatic snails—in fact a wide variety of small life which can be kept available for study at any time. Moreover, since growth is slow, it will hold filamentous algae as well as the larger plants. The tank is set up essentially as before and ‘seeded’ with the washings from wild aquatic plants, debris from the floor of a pond, scrapings from rocks and logs submerged in streams and pools, etc. Only small quantities are required for seeding. Too much will foul the water. Avoid carnivorous animals such as beetle larvae, diving beetles, etc., and above all things avoid filter-feeding animals such as freshwater clams. (Since freshwater clams and mussels can individually filter up to twenty gallons of water a day, if introduced into a tank they quickly destroy the cycle of micro-organisms.) Out of the seedings will develop a community of small animals none of which require feeding and so the organic content of the tank remains constant.
Balancing this type of tank takes time, five months or more. The aim is to produce small continuous crops of floating bacteria, unicellular plants, and protozoa for minute filter-feeders such as Daphnia etc. which in their droppings and from their dead bodies will provide fertiliser to continue the cycle, and by their feeding prevent excessive blooms (green water) of unicellular algae. Accordingly, larger aquatic plants are required to a less extent in the first planting of a tank of this type (use about one crown of Vallisneria to every two gallons of water). Growth of these plants will be
Nitella grows rapidly and is useful in the early years of these tanks because it flourishes on available nutriments but will die down quickly when starved. The quickest and simplest control of bloom organisms comes through successful seeding with pond cladocerans such as Daphnia which can be obtained in random collections. Any hint of ‘green water’ calls for more large plants and fresh seeding of the tank. Throughout the life of the tank it is sound practice to reseed at least once or twice in the year.
The theory of ‘balance’ outlined above is rule-of-thumb, but well-tested in practice. It centres on the control of the organic content of the water and of illumination by the use of larger aquatic plants so preventing blooms of microscopic plants and algae which cloud the water, fog the glass, and ‘spoil’ the tank. In general such blooms rob the water of oxygen, and some at least produce highly toxic substances such as saponins. The theory is concerned largely with the organic nitrogen cycle and takes little account of carbohydrates which are usually regarded as being balanced out by oxidation to carbon dioxide and water; but many of the breakdown products from higher carbohydrates are far too stable to be eliminated from the tank in such a simple manner and these probably increase in concentration over the years. However, this is disregarded in ordinary management but is still worth investigation. The theory recognises the importance of essential minerals and some aquarists consider that the binding-down of these substances by the larger aquatic plants is the primary factor in prohibiting blooms of algae and diatoms; but the case is not proven, and in practice all that is required is to regard the larger aquatic plants as controllable agents which permit control of the lesser elements in the tank and so bring the tank to ‘balance’.
This theory provides the answers to the many questions which are so often asked. Are snails needed to keep the glass clean? Are clams needed to filter the water? How often should the water be changed? In each case, the answer is the same—never, with a properly balanced tank, for there will be nothing to cloud the glass, fog or foul the water. Simple consideration of the theory provides the answers to all the problems which arise and places tank management on an understandable basis.
At the present time the Lycopods play a comparatively insignificant role in world vegetation, both numerically and in individual size, and for this reason they can be easily overlooked by the amateur. However, many millions of years ago, during the Carboniferous period, the ancestors of the present Lycopods and those of the related ‘Horsetails’ were among the few groups which dominated the world's plant population. The all-important flowering plants of to-day did not exist, the ancestors of the cone-bearing plants occupied a minor position similar to that of the Lycopods to-day, and even the ferns, which are now the commonest spore-producing plants, played a secondary role.
The most notable Lycopod of this age was Lepidodendron, a genus for which over 100 species have been described. The details of some of these species are known almost as well as those of many living plants, even though they have been extinct for almost 200,000,000 years. Fossilised roots, stems, leaves and fertile spikes have been closely studied and carefully correlated with one another to reveal the rather surprising fact that many of these ancient forms were large trees, attaining a height of as much as 120 feet in some cases. The tree Lycopods and tree Horsetails formed vast swamp forests, and together they played a major part in the formation of the world's most important coal fields. Insofar as modern society depends upon the major coal areas, we are that much indebted to the ancestors of seemingly insignificant groups of plants.
The Lycopods are collectively known as the Lycopsida, which is one of four classes comprising the division Pteridophyta. This division can be defined as an intermediate group of land plants which reproduce by spores, not seeds, and in the short key which follows, an attempt is made to define the four classes mentioned.
To-day only 4 lycopod genera remain—Lycopodium, Phylloglossum, Selaginella and Isoetes and the species included within these are all comparatively small plants, revealing nothing, superficially, of their former greatness.
As might be expected with remnants of such an ancient group, their distribution tends to be world-wide. For instance, of the 11 species of Lycopodium native to New Zealand, 9 occur elsewhere in the world.
Phylloglossum is more restricted, being found in New Zealand and Australia only. The one existing species is an unusual little plant, which consists of a single fertile spike and a tuft of narrow leaves arising from a tuber-like stem. Each season a new tuber is formed, which produces a spike and new leaves in the following year.
Selaginella has many widespread species. It is a genus of rather slender-stemmed plants, none of which occur naturally in New Zealand, although there is one introduced species—S. kraussiana. This is a creeping, rather delicate, shade-loving plant which is found quite commonly in some localities.
The relationships of Isoetes are rather uncertain, although most authorities now place it among the Lycopods. This mainly aquatic genus is characterised by a short, corm-like stem from which arise many long, slender leaves. A spore-producing organ occurs at the base of each leaf. There are two species of this genus native to New Zealand, and both are submerged aquatics which are distinguished mainly by size. I. Kirkii is slender and up to 12 inches high, I. alpinus is stout and up to 18 inches high or more. It almost seems as if the aquatic habit of Isoetes has protected it from the struggle for survival on the land which resulted in the extinction of its relatives.
In common with most plants, the Lycopods exhibit two stages in their life cycle. The one is a comparatively small, tuberous, underground structure which produces male and female sex organs; the other, which comes into being as a result of sexual reproduction, is what we regard as
The foregoing is a very general account of the Lycopods, but it is sufficient to show the wide scope for research on our New Zealand species. One New Zealander, the late Dr. Lycopodium, Psilotum and Tmesipteris. He published many papers describing their external variability, their internal anatomy and the nature of their tuberous sexual stage which should certainly be read by any botanist interested in the group.
Users of this key should note that species determination may be difficult in some cases, owing to the tendency of Lycopodium species to vary considerably from habitat to habitat; e.g. L. varium is usually a stout terrestrial plant which, when it is occasionally pendulous, may be very similar to L. billardieri. L. billardieri itself is notoriously variable, normally having greatly reduced fertile leaves, but occasionally plants may be found where these parts are much nearer to foliage leaves in size.
Other difficulties are the juvenile stages of L. volubile and L. scariosum, which possess only one type of leaf set all round the stem, and the peculiar case of L. densum which exhibits three types of adult leaf, which are usually on different branches. Two are long and directed outwards, the third shorter and closely appressed to the stem. The latter type is the most diagnostic and, as all three generally occur in each locality, it can be safely used as a key character.
For detailed descriptions of the species dealt with in this paper, refer to Cheeseman's Manual of the New Zealand Flora.
The following senior students contributed to this paper:—
This paper describes a group of animals illustrating differing measures of parasitic habit, examples of commonly neglected major groups, but readily accessible to the biology student. Few laboratories fail to handle the frog in the course of the year, and the frog is an excellent host harbouring a variety of protozoa, trematodes, and at least one nematode. Our common frog is Hyla aurea Lesson, introduced from Australia, and with it came an unsuspected fauna, for the parasites we have found are those known in Australia through the pioneer studies of S. Hyla aurea fails in two respects. It apparently harbours no blood protozoa nor a cestode, but the fauna is nonetheless rich and worthy of study. The species dealt with here are fairly fully described to encourage study of them.
The small Entamoeba is an active species fully illustrating the major features of Amoeba and very readily cultured. The flagellates are minute but show the anatomy and behaviour of close relatives which are significant parasites of man and his domesticated animals. Protoopalina is a ciliate, slow in movement and beautifully demonstrates ciliary action, lacks any digestive apparatus, so is a complete saprozoite having no food vacuoles. When prepared as described, some examples show various stages of mitosis. Nyctotherus is a large, transparent, slow-moving ciliate clearly showing ciliate morphology and superior in this to Paramoecium. The trematode Gorgodera is very common, and in life is transparent enough for a general study of trematode anatomy, even flame cells can be seen. It yields brilliant preparations with acetic-alum-carmine, and is excellent for practice at ‘in toto’ staining. Diplodiscus is not common and too dense for study in life. The lung nematode, Rhabdias, has an interesting life-history since it is viviparous. The larvae occur free in the frog's rectum and can live in an organically rich medium away from the host. All the above parasites survive well on a slide at room temperatures in Ringer's solution.
In the course of our work one important point has arisen. Our specimens of Nyctotherus cordiformis are all very typical of that species. Miss Raff, however, records specimens twice the usual size from H. aurea in Australia.
Entamoeba morula from Australian frogs, including H. aurea. Here again our material is half the size of Miss Raff's. Possibly a similar error in measurement has been made.
It is clear that the frog offers more than just anatomy to a biology student, and it is still a fertile host for the parasitologist since we cannot feel confident we have fully listed its parasitic fauna.
The culture medium, fixatives and stains described below should be made up before the frog is killed.
Place a live frog in a jar with a wad of cotton-wool moist with chloroform or ether, and cover tightly until the frog is dead. Then place it on its back and pin down. Cut through the skin and muscles from the pelvis to the jaws and separate the flaps to show the internal organs. Remove the gut, bladder and lungs and put them in separate glass dishes in Ringer's solution. Slit open the rectum with fine-pointed scissors. Smear some of the nearly liquid contents thinly on a slide with a scalpel blade and fix as below. Living material for microscopical examination may be prepared by adding a drop or two of Ringer's solution to the smear and lowering a coverslip on to the drop. Diplodiscus may be found in the rectum and should be removed to a watch-glass of Ringer's. To obtain Gorgodera open the bladder and remove the trematodes with a mounted needle or paint brush. Some may hold firmly to the bladder-wall. Relax these with magnesium sulphate (Epsom salts) — a few crystals on the surface of the Ringer's solution. Later they can be removed with a paint brush. Flame cells in living specimens can be made more active by the addition of a few drops of 1% urea to the Ringer's solution. Tease out the tissue of the lung with a pair of needles to obtain the nematode Rhabdias. Movement of the worm makes it fairly easy to detect.
To make permanent preparations for study, the material has to be fixed, stained and mounted. Protozoa are fixed in Schaudinn's solution, the trematodes and the nematode in hot formalin-acetic-alcohol. Iron haematoxylin is a standard stain for the parasitic protozoa; acetic-alumcarmine, for the trematodes. (Nematodes are not stained as a rule.) After staining and before mounting the material must be dehydrated and cleared. Dehydration is accomplished by placing the material in successive changes of alcohol of increasing concentration, viz. 50%, 70%, 95% and 100% ethyl alcohol. Material should then be cleared in xylol and mounted in canada balsam. A few minutes (1 to 3) in each grade of alcohol and xylol is all that is required for smear preparations, but the thicker-bodied animals such as Gorgodera and Diplodiscus will take up to 15 minutes in each step.
Formulae. (All chemicals should be C.P. standard.):—
Fixatives: Schaudinn's solution. (Poison). 100 cc. saturated solution mercuric chloride; 50 ccs. glacial acetic acid. Used cold. Leave smears in fixative for 15 mins.
Stains: Iron haematoxylin (Heidenhain's formula). Solution 1. Stain. 95 ccs. distilled water; 1 grm. haematoxylin. Heat gently to dissolve haematoxylin. To ripen solution: (a) by natural means. Put solution in a wide-mouthed bottle loosely plugged with cotton wool. Place in the sun until the solution changes to dark purple. Or: (b) chemically. Add 5 cc. carbolic acid to dissolved haematoxylin. Solution is ‘ripe’ on cooling. (The chemically ripened solution has a short life, 3 to 5 months at most. Naturally ‘ripened’ lasts a year or more.)
Staining Procedure for Iron Haematoxylin: Can be used following fixatives employing alcohol, formalin, picric acid or mercuric chloride, which must be removed by washing with water before staining; but mercuric chloride is removed from Schaudinn-fixed material by placing material in a mixture of 1 part Gram's Iodine (iodine 1 grm.; potassium iodide 2 grm.; and water 300 cc.) and 1 part 70% alcohol. After washing, place material to be stained in Solution 2 (the mordant) for 12 hours. Then Wash thoroughly by repeated changes of water. Then into a 50% concentration of Solution 1 in distilled water for 12 hours. Rinse. Destain in mordant till the cytoplasm is virtually unstained. (This process must be checked under the microscope, no exact time can be given. Nuclear chromatin should remain intensely black.) Wash. Dehydrate and clear. Mount in balsam. The slide can be hardened in an oven at 35°C. Acetic-alum-carmine:—Boil excess powdered carmine in a saturated solution of potash-alum for 15 minutes. Add 10 vols. of solution to 1 vol. glacial acetic acid. Stand for 1 week. Filter. Store in tightly-corked bottle. Dilute about 30 times with distilled water for long staining, or 1:10 for shorter. Differentiate with acid-alcohol (98 parts 70%, with 2 parts conc. hydrochloric acid).
Procedure for Nematodes:— Place the nematodes in 5% aqueous solution of glycerine with thymol (1 crystal to 200 cc. of solution) to prevent growth of mould. Leave in this solution for approximately 10 days on top of an oven or in another suitably warm position. Cover against dust. After 10 days the glycerine should have concentrated by evaporation to pure glycerine. Note:— An ample volume of solution must be used so that when concentrated the specimen is still covered. The worms can now be examined in pure glycerine or if permanent mounts are required, mounted in glycerine jelly. (This technique is useful for trematodes after staining with acetic-alum-carmine.)
Entamoeba morula Raff 1912. (Fig. 7.) A small Entamoeba agreeing with the original account (Raff, 1912) but only half the size there given. Irregularly ovoid in outline, relatively flattened. Ectoplasm generally very thin, not readily recognisable except as a more or less broad posterior sheet, often the width of the animal. Ectoplasm also extended as one or more ventral, thin small blunt lobes close to or at the anterior end. These lobes show little change in form during locomotion and are not obviously pseudopodial. Endoplasm, minutely granular, highly vacuolated in life, the vacuoles generally refractile. In fixed and stained material the vacuoles are small and moderately dispersed. Food vacuoles, numerous, generally small. Inclusions, sparse, small. Crystals, not observed. Contractile vacuole variable in position, slightly smaller than the nucleus but not observed in all animals. Nucleus large, its greatest diameter almost one-third the width of the animal, clearly visible in life, always anterior. Nuclear membrane very thin, nucleoplasm almost hyaline, nucleolus large, its width nearly half that of the nucleus, essentially central but with chromatin bridges to the nuclear membrane. Minute chromatin granules on nuclear membrane regularly dispersed, not widely spaced out. Length:—0.04 to 0.07 mm.
Found in the rectum of two frogs where it was very common. Can be overlooked because of its small size. Moderately active. Survives well on slide in Ringer's solution and cultures easily with rice starch, reproducing rapidly and surviving a month in a corked vial. (E.C.B.) Reference: Raff, 1912.
Protoopalina australis Metcalf 1923 (Figs. 8 and 9). Cylindrical, elongate, bluntly rounded anteriorly, attenuated and tapering gradually to a sharp pointed tail. Spiralled in life. In stained preparations, the tail often bent in a hook. Ectoplasm, hyaline, uniformly narrow, distinct. Endoplasm with numerous granules, but in general rather clear, non-vacuolate. Cilia longer anteriorly. Nuclei large, ovoidal, longest diameter about half greatest width of the animal, and the nuclei separated by little more than their greatest diameter. A binucleate condition is commonest, but specimens may have one to four nuclei according to their stage in fission. No nucleolus. Length 0.085 to 0.130 mm.
Abundant in the rectum of most frogs examined. Not found with P. hylarum. Moves moderately slowly, spiralling and showing a clear and beautiful ciliary action. Nuclei (0.01 × 0.0075 mm.) visible in life. Did not survive longer than two days in culture with Ringer's solution and rich starch. (J.M.) Reference: Metcalf, 1923.
Protoopalina hylarum Raff 1911 (Fig. 10). Very large, cylindrical, elongate, tapering, blunt at both ends. Our specimens green, but this not necessarily characteristic. Spiralled on the long axis in life. Pellicle, ciliation, ectoplasm and endoplasm as in P. australis. Nuclei spaced out from one another by about half the length of the animal, each being about one-third the greatest body width. Length (average), 0.42 mm.; width (average), 0.07 mm.
Occurred once in the present study, and the above account based largely on fixed and stained material. The large size of this species, about four times the length of P. australis, makes this a good species for study. (J.M.) Reference: Raff, 1911; Metcalf, 1923.
Nyctotherus cordiformis (Ehrenberg) 1838 (Fig. 12). None of our material reaches the size recorded by Raff (1911); but it agrees well with Wichterman's recent account of N. cordiformis (J. Morphol. 60 (2): 568).
A compressed ciliate, ovoidal in profile, the length/width as 7:6, the side bearing the adoral zone more convex than the other. Anteriorly obtuse, posteriorly broadly rounded but with a slight terminal subtriangular elevation. General ciliation uniform, arranged in about 25 longitudinal bands. Marginal cilia lengthen progressively around the anterior end to form a directive series of large cilia as an adoral membrane continuous with the membranelle of the cytopharynx. The peristome is elongate, narrow, directed antero-laterally, and just less than one-third of the total length of the animal. The long cytopharynx extends obliquely across the animal but curves to terminate somewhat longitudinally at the cytostome. Cilia are present along the anterior face of the cytopharynx. Pellicle relatively thin; body, flexible. Ectoplasm hyaline, thin. The endoplasm, granular, sparsely vacuolated with relatively small vacuoles, but in some richly vacuolate. A single contractile vacuole situated at the posterior end, constant in position. Nucleus densely granular, its length about 2½ times its width, reniform and constantly located obliquely across the body parallel and near to the cytopharynx.
Micronuclei not observed. Division apparently rare, not observed. Does not reproduce rapidly in culture. Length: 0.13 to 0.145 mm.; width: 0.09 mm. to 0.125 mm.
Occurred in the rectum of most frogs examined. A large transparent ciliate, slow-moving and from its form and transparency ideal for study, even showing the nucleus clearly in the living specimen. Movement of the cilia relatively slow and beautifully manifest. Survives well mounted in Ringer's solution on a slide. Cultures readily in Ringer's solution with rice starch in a corked vial for a month. Best studied alive, but stains attractively with iron haematoxylin. (P.A.M.) Reference: Kudo, 1947; Raff, 1911; Wichterman, 1936.
Copromonas subtilis Dobell 1907 (Fig. 13). A small pyriform flagellate pointed anteriorly, broadly rounded posteriorly, and apparently ovoidal in cross section. Length slightly more than twice greatest width. Pellicle appears plain, very thin. Ectoplasm, hyaline, very thin. Endoplasm, finely granular; in fixed and stained specimens richly but finely vacuolated. Numerous small non-vital inclusions in the endoplasm. Flagellum, as seen, about the length of the body. Nucleus poorly defined, granular, slightly anterior and the diameter no more than one-third the greatest width of the body. Cytostome not observed. Length: 0.011 mm.; width: 0.0045 mm.
Not common in the rectum of frog examined, but described by Raff (1911) as the commonest flagellate in the intestine. In life, this is a relatively slow-moving flagellate, but difficult to study owing to its small size. Was not cultured in rice starch with Ringer's solution. (B.R.C. and R.B.C.) Reference: Kudo, 1947; Raff, 1911.
Eutrichomastix batrachorum (Dobell) 1907 (Fig. 14). A small spindle-shaped flagellate, anterior end bluntly tapered, posteriorly attenuated as a tail about half the body length. Pellicle and ectoplasm very thin, endoplasm finely granular with two very large vacuoles obvious in stained specimens. Three long thin anterior flagella and one thin posteriorly directed flagellum approximately the same length as the anterior. Nucleus oval, thickly granular, located anteriorly, well-defined; but not visible in live specimens. A single kinetoplast situated at the anterior end. Axostyle not observed in stained material. Length: 0.015 mm.; width: 0.0045 mm.
In large numbers in Schaudinn-fixed smears of rectal contents stained with iron haematoxylin. When detected were abundant. Swims with an undulating jerky movement. In living specimens the tail appeared to have a swelling halfway along its length; but not in the stained specimen. Thrived for over three weeks in culture of Ringer's solution with rice starch in a corked vial. (B.R.C. and R.B.C.) Reference: Kudo, 1947; Raff, 1911.
Tritrichomonas batrachorum (Perty), (Fig. 15). Somewhat lemon-shaped, the body generally rounded but extended anteriorly and posteriorly, bluntly rounded at these extremities. Pellicle and ectoplasm very thin. Endoplasm minutely granular with a few small scattered vacuoles. A few minute granular inclusions. Axostyle not observed in fixed and stained specimens. In fixed and stained specimens, three short anterior flagella each less than half the body length, and
Only a few typical specimens seen in a Schaudinn-fixed haematoxylin stained smear of rectal contents. Possibly more common in the small intestine. In life minute, but recognisable by a somewhat jerky movement. Did not fix well, many specimens collapsing. Stains well with iron haematoxylin. (B.R.C. and R.B.C.) Reference: Kudo, 1947; Raff, 1912.
Diplodiscus megalochrus Johnston 1912 (Fig. 6). A thick-bodied, bluntly cenical trematode generally circular in section, tapering anteriorly from the posterior region. In life convex dorsally, venter broadly concave longitudinally. Skin, thick but without spines or spicules. Oral sucker, about one-tenth of body width, surrounded by a less obvious narrow ring of muscle as if an additional attachment organ. Acetabulum posterior, subterminal, about three times the width of the oral sucker and surrounded by a prominent ring of muscle, three-quarters of
Found in rectum of three frogs. When present, as many as eight in one frog. A thick skin conceals detail in the live specimens but good preparations with acetic-alum-carmine can be made from large specimens flattened gently during fixation. Young specimens move with an extreme attenuation of the body, extending it to at least twice its resting length. (J.C.Y.) Reference: Johnston, 1912.
Gorgodera australiensis Johnston, 1912 (Fig. 1). A flat trematode, narrowly oval in cross section, tapering anteriorly in a highly mobile preacetabular region but wider and less mobile posteriorly. Oral sucker about two-thirds the width of the acetabulum which is about half the width of the posterior region and slightly more than the width of the anterior region of the body. Skin smooth, no spines. Mouth at base of oral sucker followed by a short oesophagus dividing just posterior to the oral sucker. Limbs of the intestine narrow, tubular, and extending almost to the posterior end of the body. Nine testes, each irregularly lobed, arranged in two longitudinal series of four and five respectively, connected longitudinally by delicate vasa deferentia which unite near the anterior margin of the acetabulum opening into a vesicula seminalis which passes into the cirrus. A single smoothly-lobed ovary level with the anterior testis. Two compact yolk glands are arranged as a transverse pair anterior to the gonads and immediately posterior to the acetabulum. Transverse vitelline duct occasionally visible. The convoluted uterus extends posteriorly as a median narrow tube between the gonads to the posterior end of the body, and anteriorly as two branches lateral to the intestine up to the level of the ovary. The median branch extends dorsal to the acetabulum to terminate at the female aperture in the common genital atrium. Common genital aperture immediately posterior to fork of the intestine. Length of body: 4.0 to 6.0 mm.; width: 0.75 to 1.5 mm.
A common trematode of the bladder, present in all frogs examined with 3 as a minimum and 24 as a maximum and averaging about 5 per frog. The living worm transparent, so that much internal anatomy is visible, and even flame cells can be seen. Specimens can be kept alive at least five to six hours in Ringer's solution. Stains brilliantly with acetic-alum-carmine. (B.G.McF. and J.B.N.) Reference: Johnston, 1912; Dawes, 1946.
Rhabdias hylae. Johnston and Simpson, 1942. (Figs. 3, 4, 5.) Body stout, tapering gradually anteriorly from the level of the base of the oesophagus, and posteriorly tapering rather abruptly from the level of the anus to a short conical tail. The dark-brown pigmented intestine is characteristic.
Cuticle thin, with faint longitudinal striations. All specimens examined showed the appearance of a ‘halted’ moult, each worm being enclosed in a wrinkled cuticular envelope. Mouth, surrounded by six very low, scarcely-discernible lips, opens into a short buccal capsule. Oesophagus, muscular throughout, with a slight posterior swelling; its length approximating one-seventh of total body length. Straight, thick-walled intestine constricted slightly posteriorly, expanding again before joining the short rectum opening at the sub-terminal anus. Vulva prominent, situated near the middle of the body, opening directly into the opposed uterine branches. Ovaries, reflexed; but much of the reproductive system is concealed by the pigmented intestine. Eggs containing advanced embryos can be seen in the distal portions of the uterine branches. Total length: 5.5 mm.; maximum diameter: 0.39 mm.; length of tail: 0.37 mm.
Barely 10% of the frogs examined were infected. An interesting fact is that all specimens were ‘female’ forms (protandrous hermaphrodite), this being the parasitic generation. Probably a free-living sexual generation occurs. The specimens were cleared in glycerine for examination and mounted in glycerine jelly. (J.M.McE. and R.J.S.) Reference: Baylis and Daubney, 1926; Johnston and Simpson, 1942.
This literature can be obtained through the Library Exchange Service.
The Animals considered here are all, with the exception of the lamprey, marine aquatic chordates, and although much varied in size, ranging from Cephalodiscus where the individuals are only 1/25th of an inch to the basking shark of 40 feet, and as varied in form, these chordates differ from all others in the absence of bone. Some are only of academic interest but many of the others, the rays and sharks, are of considerable economic value and popular interest.
Sharks share much of the evil reputation of snakes. True enough, fatalities from sharks are definitely established for several species, and even for local waters. A tombstone in the Boulton Street Cemetery, Wellington, records the death of a soldier killed by a shark many years ago in Lambton Harbour, and other cases are in the records; but in fact attack by sharks is relatively rare, even in Australian waters where the risk is less than any other violent danger to which the average citizen of that country is exposed. The majority of sharks are of small size, harmless to man, predators on fish, crabs, molluscs and other small life in the sea. Our largest shark, the basking shark, is as harmless as a whale. If people could appreciate the difficulties in establishing records of actual attacks on man by sharks, the common fear of the shark would be greatly diminished, and we would come to a better recognition of their place and value. In various parts of the world these fishes form the basis of a profitable industry. In Florida it is now recognised that the sharks taken in shallow waters are only the stragglers from the great shark populations which live in 500 fathoms and more. The future scope of shark industries is still unmeasured, but the meat of many species is excellent, is now exported, and has been eaten in no small quantity by New Zealanders in recent years; the skins provide excellent ornamental leathers; the livers yield vitamin-rich oils. Dried fins of sharks and rays, and other parts, are exportable, as well as in demand in this country for food. The proper utilisation of these fishes will be an important addition to the fisheries of this country.
At the present time we can recognise some 29 species of sharks and eight, or possibly nine, rays in our waters, the majority being little known and less studied. Unfortunately it is rare for larger specimens, and even
This account aims at facilitating the study of the sharks of these waters by providing a convenient guide. We do not regard it as being either complete or systematically final. It is condensed from extended data based on studies by Archey, Fowler, Phillipps, Whitley, Waite, and others. Fortunately, Bigelow and Schroeder in their recent magnificent work — ‘Fishes of the Western North Atlantic’—have considered the systematic status of many of our sharks and we profit greatly from their studies which provide data for the careful comparison of New Zealand material with the species of their area. Where possible we have reviewed the status of our species, but all the problems are not solved. Decision on the correct generic name of the basking shark — Halsydrus, Tetroras, or Cetorhinus — may better be determined overseas, but it is for the New Zealand worker to settle such problems as the specific identity of many of our species. In reviewing the common spotted dogfish, we find that it was identified by Waite as Squalus fernandinus on the basis of an account by Tate-Regan. Phillipps compared our species with a more recent account of S. fernandinus, found the two distinct, and named ours S. kirki. But S. fernandinus belongs to a group of short-bodied species in the genus Squalus. Our species is elongate, and it is Norman who pointed out that the material Tate-Regan dealt with is elongate and actually belongs to the South American S. lebruni. Norman, comparing specimens from the two areas, could not separate ours from S. lebruni, nor can we at this time distinguish the two. There still seems difficulty about the true mako. Overseas workers favour the opinion that there is only one species, Isurus glaucus, in the Pacific; but Phillipps has given an account of a mako having a more elongate form and with a relatively smaller dorsal. A cast and a specimen in the Dominion Museum gives us no basis for the separation of our Prionace from P. glauca. Fraser-Brunner has now cleared up points in Whitley's account so that we can recognise our hammerhead as Sphyrna lewini. Specimens of Dalatias from Cook Strait are identical with D. licha. We are unable to distinguish juvenile bramble sharks fished in Cook Strait from Echinorhinus brucus.
In general there is need for the examination of much further material for nearly all species, and the results from such work will have considerable ichthyological value. The greater part of our shark fauna is made up of cosmopolitan species, sharks which are apparently from deeper waters.
Where possible, the figures used here have been drawn from specimens. It is the practice to always figure the left aspect of animals so that comparison between figures is simplified. In re-drawing from some authors and casts it has been necessary for us to reverse the figure to maintain this standard. Figures have been re-drawn from authors as follows: Archey, 34; McCoy, 44; McCulloch, 10; Morton, 2; Phillipps, 39; Whitley, 24, 30. The following are based on casts in the Dominion Museum: 18, 19, 20, 22, 23, 25, 26, 27, 31, 35. In this guide the reference numbers, e.g. 1 (10) in the key below, are alternatives. Where there is not agreement with 1 refer to 10. Where the agreement is with 10, then proceed to the next number, i.e. 11, etc.
(10) The body simple, not divided into the usual head with well-formed eyes, etc., and trunk of many segments, but as follows:
(7) Body consisting of a proboscis (prb.), a collar (coll.) and a trunk of few or many segments.
(4) With many tentacles. Proboscis flattened to a disc surrounded by marginal tentacles rising from the collar; 1 pair, or no gill-slits; trunk U-shaped, the anus near the mouth. ( Pterobranchia — regarded by some as non-chordate.)
(3) Lacking tentacles about the mouth. Proboscis somewhat acorn-like; collar cylindrical; body elongate, worm-like; 5 or more pairs of gill-slits; anus terminal. ( Enteropneusta.)
(6) Dorso-lateral genital wings (g.w.) developed; up to 40 pairs of gill-slits. Balanoglossus australiensis (Hill) 1895. (Fig. 2.) In shallow burrows in fine sand at low tide levels; yellowish, brown and creamy white. Up to 200 mm. Known from Auckland area, and possibly Christchurch on the basis of a larval specimen taken near the latter.
(5) Genital wings lacking; few (12) gill-slits; a groove along the proboscis. Saccoglossus otagoensis (Benham) 1899. (Fig. 3.) Among coralline seaweed, holdfasts of kelp, etc. Bright red to orange. Up to 40 mm. and more. Common Wellington to the south.
(2) No proboscis or collar; body not worm-like.
(9) The body commonly U-shaped; enclosed in a gelatinous test which may be more or less transparent, or opaque and leathery; sedentary or pelagic; solitary or colonial. Tunicata. A large, diverse group requiring separate treatment.
(8) Body straight, naked, compressed, pointed at each end, with many distinct segments; gonads serial. Cephalochorda. Represented here by
(1) A well-formed distinct head usually with well-developed eyes moved by muscles; the mouth either surrounded by a disc or with opposable jaws supported by skeletal elements; a trunk of many segments and a segmented postanal tail; 14 pairs or less of gill-slits; gonads not segmental in the adult; etc. Craniata.
(16) The mouth surrounded by labial folds which extended may form a disc or contracted are more or less vertical; the folds armed or not with teeth; tongue, protrusible, toothed; a single median nostril; eel-like but without scales or paired appendages. Cyclostomata.
(15) Snout with barbels; labial folds not toothed; eyes vestigial, concealed; nostril terminal; no separate dorsal fin.
(14) One pair of external branchial apertures placed one on either side of the midventral line. (Myxinidae.) Myxine biniplicata Richardson and Jowett 1951. (Fig. 5.) Hagfish. Unique in the possession of short ventrolateral paired fins alongside and forward from the branchial apertures; pinkish-white. Not slimy. Up to 16 inches. Trawled in Cape Campbell area.
(13) Gill-pouches open separately so that there are several (5 to 14) apertures spaced out on either side. ( Eptatretidae.)
(12) Snout without barbels; nostril remote from rim of well-developed oral disc; eyes functional; separate dorsal fins; 7 pairs of branchial apertures. (Mordaciidae.) Represented here by Geotria australis Gray 1851. (Fig. 7.) Lamprey. Edible. Spawned in sandy patches along river margins, develops to a toothless ammocoetes larva½ in. in length, and metamorphoses at 3 to 4 inches to a toothed, large-eyed macrophthalmia which moves downstream to the sea. Returns to freshwater as a velasia stage of 20 inches which matures to the adult, possibly without feeding and in the male with an increase in diameter of the oral disc and the formation of a large pouch below the throat. The teeth vary in these different stages.
(11) Mouth more or less transverse and supported by jaws; paired pectoral and pelvic appendages generally present. Gnathostomata.
(24) Paired appendages present as fins which have a web wholely supported by fibres of ectodermal origin; endoskeleton cartilaginous; gill-slits, 7 pairs or less. Chondrichthys.
(21) Gill-slits concealed beneath a fleshy fold so that there is but one external aperture (as in bony fish); four pairs of gills; adult skin lacks denticles; dorsal spine and fin both depressible. Holocephali.
(20) Snout extended and supporting a flexible flap-like lobe; pectorals nearly reaching pelvics; lateral line, a closed tube excepting for numerous apertures.
Callorhynchus milii Bory 1823. (Fig. 8.) Elephant fish. Very common. Edible. Up to 40 inches. In our material the pectoral barely reaches to the pelvics and falls short of second dorsal differing thus from C. callorhynchus.
(19) Snout obtusely angled; no distinct anal fin; caudal filamentous butshort, longer in young; lateral line, an open groove. Chimaera novae zealandiae Fowler 1910. (Fig. 9.) Ghost shark. Exceeds 2 feet.
(18) 5 to 7 pairs of gill-slits opening separately at the surface; dorsal spine (if present) and fin not depressible. Elasmobranchii.
(23) Gill-slits ventral; body more or less strongly depressed (flattened from above); anterior margin of pectoral fused with head to form a disc Batoidei (skates and rays).
(22) Gill-slits lateral; pectoral fin with a free anterior margin. Selachii (sharks).
(17) Web of fins supported by segmented rays; skeleton of bone; gill-slits open into a common branchial chamber covered with a fleshy flap supported by a bony operculum. Osteichthys. (Bony fishes.) A large and diverse group requiring separate treatment.
(4) Disc narrow, the width less than half of total length; nasoral grooves short or absent; usually 2 dorsals; caudal well-developed.
(3) Pectorals not reaching to end of snout (F. Rhinobatidae); first dorsal well behind ventrals; front nasal valves confluent forming a quadrangular flap across front of mouth. (Trygonorrhina fasciata Muller and Henle 1841. (Fig. 10.) Fiddler ray. Up to 4 feet. Doubtfully a member of our fauna: but a shovel-nose Aptychotrema banksii has also been listed here, so one may occur in our waters.)
(2) Pectorals extend to end of snout (F. Platyrhinidae); one dorsal fin; rostral cartilages absent; nasal flap triangular but deeply incised: above, everywhere thorny. Arhynchobatis asperrimus Waite 1909. (Fig. 11.) Known only from (?) one specimen, Bay of Plenty. 26 inches.
(1) Disc broad, the width half or more of total length; nasoral groove well developed.
(10) Teeth raptorial; skin smooth; disc depressed, rounded, anteriorly obtuse; well-developed electric organs (F. Torpedinidae).
(7) 2 dorsals; tail short; disc large, subcircular; pelvic fins not united (G. Torpedo); no fringe on margin of spiracle; base of first dorsal ends even with base of ventral. Torpedo fairchildi Hutton 1872. (Fig. 12.) Electric skate. Up to 40 inches. (In the literature as Narcacion, Narcobatus, Notastrape, and T. fusca.)
(6) 1 dorsal; front portion of pelvics modified as for walking, posterior portion fused to disc; eyes rudimentary. (G. Typhlonarke.)
(9) Disc circular, the outline broken only by notch under tail; tail short; pelvics short, blunt, not reaching to margin of disc. T. aysoni (Hamilton) 1902. (Fig. 13.) Numb-fish, cramp-fish. Up to 3 feet. Possibly not north of Cook Strait.
(8) Disc obtuse anteriorly, elongate, not notched below caudal; pelvics short, blunt, but reach to or beyond margin of disc; peduncle little compressed. T. tarakea Phillipps 1929. (Fig. 14.) Up to 13 inches. Possibly not north of Cook Strait.
(5) Teeth pavement-like; disc broad, angular or rounded.
(14) Pelvis transverse; usually two small dorsals with rays, but caudal membranous and more or less imperfect (F. Rajidae); rostral cartilage elongate; teeth small, numerous. (G. Raja.)
(13) Body largely roughened, smooth patches small; a single row of major vertebral spines only on the tail with a minor row on each side also in older specimens; tail slender, long, its length reaching from origin to beyond eyes. R. nasuta Muller and Henle 1841. (Fig. 15. Disc spines not shown.) Skate. Up to 30 inches. (Shows greater variation than yet described.)
(12) Body with large smooth patches; snout not greatly extended, but sharp pointed; a single row of major vertebral spines with as many as 2 minor rows on each side of tail; tail stout, short, its length barely reaching from its origin to eyes. R. lemprieri Richardson 1846. (Fig. 16.) Skate. Up to 5½ feet. (Possibly the R. australis of Macleay, 1881, since N.Z. specimens have the more pronounced acute rostrum and other features of Macleay's species.)
(11) Pelvis arched anteriorly; one dorsal, or none; tail slender, lacking rayed fins, whip-like.
(16) Teeth broad, molar-like, the medians commonly the wider; disc transverse, lateral angles acute (F. Myliobatidae); snout and head smoothly rounded; teeth in 7 rows; first dorsal origin at the length of its
Holorhinus tenuicaudatus (Hector) 1877. (Fig. 17.) Eagle-ray. Up to 4 teet. (In literature as Myliobatis.)
(15) Teeth small, pavement-like; no horn-like processes at sides of head; disc as wide as long (F. Dasyatidae), quadrangular; tail with a serrated spine (G. Dasyatis). Sting-rays, the serrated spine causing a deep and potentially dangerous wound.
(18) Tail short (subequal to length of disc), heavy, compressed; tip of serrated spine reaching beyond mid-point of tail; ventral fold on tail, deep; tail armoured on sides with wellspaced dises each bearing an erect conical sharp spine; a row of a few large spaced-out spined plates anterior to serrated spine but not extended far on to dorsum of disc. D. brevicaudatus (Hutton) 1875. (Fig. 18.) Growing to 14 feet long in Australia, but known here to 8 feet.
(17) Tail long (equals 1½ times length of disc), slender, the terminal portion cylindrical; serrated spine anterior on tail and not reaching to midpoint in length of tail; ventral fold, narrow; tail armoured with crowded discs generally contiguous, and each bearing an erect conical sharp spine; a row of large spined plates anterior to serrated spine extends on to disc, with a row on either side. D. thetidis Waite 1899. Known here to 10 feet long, but a larger specimen estimated 11 feet long taken by the ‘Maimai’ in Cook Strait in 1951.
(8) Anal fin present.
(5) 6 or 7 gill apertures; only one dorsal fin.
(4) Margin of gill-openings lateral, not extending across throat; upper teeth notably dissimilar from lower on either side of symphysis. Notidanoidea.
(3) Margin of gill-openings extend beneath and across the throat; teeth of upper and lower jaws similar; elongate, rather eel-like. Chlamydoselachoidea. Rare. Not as yet known from our waters.
(2) Only 5 gill openings; 2 (rarely 1) dorsal fins.
(7) A stout spine in front of each dorsal fin; teeth near symphysis in each jaw markedly smaller and differing from those toward the corners. Heterodontoidea. (Possibly represented here by
(6) No spines before the dorsal fins; median teeth basically similar to laterals. Galeoidea.
(1) No anal fin.
(12) Snout, shark-like, of moderate length, not beak-like, without lateral teeth and barbels.
(11) Trunk subcylindrical to subtriangular; shark-like; eyes lateral; anterior margin of pectorals not overlapping gill openings. Squaloidea.
(10) Trunk depressed, skate-like; eyes dorsal; anterior margin of pectorals far overlapping gill openings. Squatinoidea (Apparently not yet known from our waters.)
(9) Snout elongate, flattened, armed with lateral teeth and bearing a long fleshy barbel. Pristiophoroidea. (Unknown from our waters.)
(4) 7 gill apertures on each side; head broad; snout broadly rounded. G. Notorynchus.
(3) No median tooth in the upper jaw. (N. cepedianus (Peron) 1807. Sandy-grey with scattered round black spots; up to 8 feet and more; presence doubtful.)
(2) A single median tooth in the upper jaw. N. pectorosus (Garman) 1884. (Fig. 19.) Brown above, paler below; upper surface irregularly sprinkled with darker spots or specks; up to 8 feet. (Note: the sharp-snouted, 7-gilled Heptranchias with the horizontal diameter of the eye much greater than the internasal space should be watched for here. The anal commences well under the dorsal in
(1) 6 gill apertures on each side. Hexanchus griseus (Bonnaterre) 1780. (Fig. 20.) Cow-shark. Immaculate dark grey to almost black, or with a longitudinal lateral streak; up to 26 feet; sluggish in habit; known from depths of 500 fathoms and more.
(2) Base of the first dorsal fin terminating posterior to origin of pelvic fins. (F. Scyliorhinidae.) Cephaloscyllium isabellum (Bonnaterre) 1788. (Fig. 21.) Carpet-shark; swell-shark; no labial furrows on either jaw; brown above with dark bands alternating narrow and wide; up to 8 feet; can inflate the stomach with water or air.
(1) Base of first dorsal ends above or well anterior to origin of pelvics.
(26) Head shaped as usual in sharks; not forming a ‘hammer’.
(11) Tail strongly lunate; lateral keels on caudal peduncle.
(10) Teeth large, relatively few (25 to 50); no gill-rakers. (F. Isuridae.)
(9) Teeth of upper jaw long, narrow, slender, smooth-edged.
(8) No lateral denticles on any teeth; first 2 teeth in each jaw more slender and flexuous than the others; 1 keel on side of caudal region. Isurus glaucus Muller and Henle 1841. (Fig. 22.) Mako or blue-pointer. Dark navy-blue above, whitish below; regarded as dangerous; up to 13 feet. (I. mako Whitley is regarded by Bigelow and Schroeder as probably identical with I. glaucus. A cast in the Dominion Museum suggests the atlantic I. oxyrinchus more than I. glaucus.)
(7) First 2 teeth in each jaw similar to succeeding teeth; teeth mostly with lateral denticles; a secondary lateral keel on anterior part of caudal fin below the peduncular keel. The Lamna whitleyi described by Phillipps, 1935, is possibly separable from L. nasus (Bonnaterre) 1788, and needs careful investigation. (Fig. 23.) Porbeagle. Slate-grey on back and sides; lighter below; up to 10 feet.
(6) Upper teeth broadly triangular, edges serrate; strongly lunate tail. Carcharodon carcharias (Linn) 1758. (Fig. 24.) White shark. Brown to grey above, white on sides and below; up to 30 feet and larger; regarded as most dangerous.
(5) Teeth minute, numerous (4 or more to the inch), conic not serrate; gill-rakers present. (F. Cetorhinidae.) Cetorhinus maximus (Gunnerus) 1765. (Fig. 25.) Basking shark. Grey above, paler below; up to 40 feet. The skeleton washed ashore often mistaken for that of a sea-serpent; the gill-rakers, being long, are mistaken for hair. Any specimen should be most carefully checked. (The Australian C. maccoyi which has a relatively longer tail and higher first dorsal may extend here.)
(4) Caudal not lunate.
(13) Caudal extended to equal nearly half the total length of the animal. (F. Alopiidae.) Alopias vulpinus (Bonnaterre) 1788. (Fig. 26.) Thresher shark. Grey to black above, white below; up to 25 feet. A. caudatus Phillipps is most doubtfully distinct.
(12) Caudal considerable less than half of the total length; opening of fifth gill above or behind origin of pectoral.
(17) Teeth low, mosaic- or pavement-like, small, several series functional. (F. Triakidae.) Nostril not connected to mouth (G. Mustelus).
(16) Many small white spots; origin of first dorsal immediately posterior to base of pectoral; pectoral reaches middle of first dorsal; third gill-opening the largest. Mustelus lenticulatus Phillipps 1932. (Fig. 32.) Spotted gummy-shark, smooth bound. Grey with many conspicuous small white spots; up to 3 feet.
(15) Some few light spots; origin of first dorsal well behind axilla; pectoral does not reach middle of first dorsal; first gill-opening, largest. M. antarcticus Gunther 1870. Gummy shark. Grey above, whitish below; up to 3½ feet and more.
(14) Teeth triangular, compressed, sharp, only 1 (or 2) series functional. (F. Carcharinidae.)
(21) Spiracles present, may be large or minute; anal base short.
(20) Caudal peduncle with a low lateral dermal ridge; spiracle minute; snout short; teeth, large, serrate, and tips oblique. Galeocerdo cuvier (Lesueur) 1822. (Fig. 30.) Tiger-shark. Slate-grey, irregular banding on back; up to 18 feet. Even if species of Australasian waters is not the same as elsewhere, it has priority in this name.
(19) No peduncular dermal ridge; no precaudal pits above or below; teeth with denticles, cusps narrow, oblique and not serrate. Galeorhinus australis (Macleay) 1881. (Fig. 31.) School shark. Grey to brown above, lighter below; up to 6 feet and more.
(18) Spiracles absent.
(23) Midpoint of base of dorsal considerably nearer to origin of pelvics than to axilla. Prionace glauca (Linn) 1758. (Fig. 29.) Blue shark. Brilliant blue above, white below; up to 15 feet and more. (P. (syn. Glyphis) mackiei Phillipps is inseparable from P. glaucus.)
(22) Dorsal anterior, the mid point of the base nearer level of axilla than to level of origin of pelvics; margins of cusps of upper teeth regularly serrate, lowers serrate or smooth.
(25) Second dorsal smaller than and placed above the anal; apex of first dorsal, acute; cutaneous ridge between dorsals. Carcharhinus brachyurus (Gunther) 1870. (Fig. 27.) New Zealand whaler. Uniformly grey; up to 9 feet. (Recorded previously in our literature as Carcharias and
(24) First dorsal with apex obtuse or rounded; second dorsal larger than and commencing slightly anterior to anal. (? Eulamia lamia. The shark listed under this name in our literature is systematically doubtful. The figure (Fig. 28) after Phillipps is possibly Carcharhinus leucas. The probability is that a
Carcharhinus is present in our waters. It may lack a cutaneous fold between the dorsals.)
(3) Head expanded laterally to form a ‘hammer’. (F. Sphyrnidae.) Sphyrna lewini (Griffith) 1834. (Fig. 33.) Hammerhead shark. Recorded formerly as S. zygaena. Other species may be present and can be recognised in a different contour of the hammer.
(16) A spine at the front of the base of each dorsal ( (13) Teeth dissimilar in the two jaws. (12) Snout short, its length from mouth considerably less than from mouth to origin of pectorals; dermal denticles short, rising from a short broad stem. (11) Body shark-like, not strongly compressed and not forming an acute triangle in section. (8) Inner corner of pectoral broadly rounded; nostrils oblique; scales pedunculate and with 3 or more strong keels. (7) Anterior end of base of second dorsal is posterior to the anterior end of pelvic fin; pectoral fin does not reach to base of first dorsal; dorsal spines concealed. (6) Anterior end of base of second dorsal above or close behind anterior end of base of pelvic fin; pectoral nearly reaches to anterior end of base of first dorsal which is situated in the first third of the body-length. (5) Inner corner of pectoral angular and somewhat produced; nostrils transverse; scales on trunk leaf-shaped with a strong median keel. (10) Dorsals relatively large, base of first dorsal longer than that of second; median erect tooth in lower jaw; some denticles tridentate but without long sharp prongs. (9) Dorsals relatively small, base of first as measured from spine shorter than of second; some dermal denticles elongate, narrow and sharp-pronged. (4) Body stout, strongly compressed and an acute triangle in section; spines arise from base of dorsals. (3) Snout long, its length from mouth nearly reaches from mouth to pectoral origin; dermal denticles trifid, elongate, sharp, rise from a narrow stem;
(2) Teeth similar in both jaws. (15) First dorsal rises close to axilla. (14) Anterior margin of nostril with a single point; first dorsal rises well behind axilla; (1) Second dorsal, and usually the first, without a spine in front. (20) Teeth with only 1 cusp; upper teeth, narrow, raptorial; lower teeth expanded, sectorial. ( (19) Lower teeth erect, triangular, nearly symmetrical, serrate; head truncate; eyes large. (18) Lower teeth strongly asymmetrical, not serrate but having the outer margins notched; head depressed; eyes small; branchial apertures very small; dorsals sub-equal. (17) Teeth sectorial in both upper and lower jaws, each tooth with several cusps; snout broad and tapering. (
F. Squalidae).G. Scymnodon.S. sherwoodi Archey, 1921. (Fig. 34.) Dark-brown, lighter below; up to 3 feet.S. plunketi (Waite) 1910. (Fig. 35.) Uniform dark-brown; up to 5 feet.G. Centrophorus.C. nilsoni Thompson 1930. (Fig. 36.) Brown above, lighter below; up to 3½ feet; from Kaikoura.C. waitei Thompson 1930. (Fig. 38.) Brownish black; length 13 inches; Kaikoura. (? Juvenile of S. plunketi.)Oxynotus bruniensis (Ogilby) 1893. (Fig. 41.) The prickly dogfish; uniform sandy-brown; growing to 2 feet.Deania kaikourae Whitley 1934. (Fig. 37.) Uniform dark-brown; up to 3½ feet; Kaikoura and Cook Strait.G. Squalus.S. griffini Phillipps 1931. (Fig. 39.) Brown, immaculate; up to 3 feet and more; North Island. (Possibly the heavy-bodied S. fernandinus.)Squalus lebruni (Vaillant) 1888. (Fig. 40.) The spotted dogfish. Greyish with conspicuous white spots; up to 3 feet 6 inches. Still requires complete description.F. Dalatiidae.)Dalatias licha (Bonnaterre) 1788. (Fig. 42.) Black shark. Uniform violet-black or dark-brownish; up to 4 feet 6 inches. D. phillippsi is regarded as inseparable from D. licha, but McCulloch shows a fimbriated rectangular nasal flap which is acutely triangular in D. licha and our specimens.Somniosus antarcticus Whitley, 1939. (Fig. 43.) The sleeper shark. Inadequately known from one specimen, 8 feet 6 inches long, washed ashore at Macquarie Island, hence possibly in our waters.F. Echinorhinidae.) Echinorhinus brucus (Bonnaterre) 1788. (Fig. 44.) The spiny or bramble shark. Purplishbrown, paler below, spotted darker; up to 8½ feet.