page 2

Supplementary Keys to the Collembola

The following corrections to the original key should be noted:—

• Page 4, line 4 from top: "always" should read "usually."
• Page 7, line 40 from top: "(722)" should read "(695)"
• Page 7, line 43 from top: "(812)" should read "(785)"
• Page 9, line 12 from bottom: "(1232)" should read "(1297)"
• Page 11, line 26 from top: "(1133, 1028)" should read "(1141, 1028)"
• Page 14, line 22 from bottom: Delete "Nicolet, 1847 (801)"
• Page 18, line 10 from bottom: "(797)" should read "(798)"
• Page 18, line 23 from bottom: "1902 (1138)" should read "1901 (1135)'
• Page 19, line 18 from top: "Folsomia" should read "Folsomina"
• Page 19, bottom line: "(944)" should read "(916)"
• Page 20, line 6 from bottom: "(1055)" should read "(1027)"
• Page 22, line 25 from top: "(782)" should read "(784)"
• Page 22, line 8 from bottom: "(159)" should read "(149)"
• Page 29, line 2 from top: "(1159)" should read "(1131)"
• Page 29, line 18 from bottom: "(374)" should read "(373)"

The families Palpigeridae and Catastylidae Olfers, mentioned on pages 4 and 17, should be completely deleted from the keys, as the material upon which Olfers founded his species, genera, and families has been proved by E. Handschin to be artefacts. This has been confirmed in a letter to me by Handschin since my Keys were published.

Among recent published works on the Collembola, possibly the most far-reaching in their effects on taxonomy are the two papers by Cassagnau, the one dealing with the effects of temperature on the morphology of Hypogastrura purpurascens (Lubb.), the other with with the mouth parts of the Neanuridae. In this latter paper, Cassagnau shows a transition in mouth part development which appears to link the Pseudachorutini, Anuridini, and Neanurini into one large family, the Neanuridae. This brings together a vast assemblage of genera of widely divergent body form and mouth parts, which seems to me to be undesirable, but it does point the way to a perhaps more definite grouping of these widely divergent forms. Cassagnau based his conclusions on the study of fourteen genera, whereas some 64 related genera are involved in his suggested reclassification. On applying his principles to my Keys to the Collembolan Families, etc., it appeared to me that the classification given on page 4 of my Keys and Bibliography might be amended in the following fashion:—

7.	Mandibles with well-defined molar area	Sub-family Hypogastrurinae
	Mandible without molar area or entirely absent	8
8.	Mandible present, maxilla elongated, often needle-like, with or without teeth and lamellae	9
	Mandible usually absent, but, if present, then without molar area but usually with some apical teeth, often hatchet-like in shape; maxilla broadened apically, often claw-like or triangular in shape, with teeth and sometimes with lamellae	Sub-family Brachystomellinae page 3
9.	Maxilla head with numerous teeth and bearing one or more distinct, strongly developed fringed or toothed lamellae	Sub-family Anuridinar
	Maxilla head styliform with or without indistinct, poorly developed lamellae; teeth if present being apical only, never forming fringes, often rudimentary and usually only 2–3 in number, never more than 6	10
10.	Abl. VI either wholly or partly covered by Abd. V or enclosed by Abd. V; pleural areas of body often more or less swollen and separated off as paratergites	Sub-family Pseudachorutinae
	Abd. VI large and usually bilobed, integument coarsely tuberculate; the body segments usually with large bosses	Sub-family Neanurinae

Our knowledge of the structure of the mouth parts of the great majority of the 64 genera involved in such a reclassification as this is incomplete or non-existent, and I find, therefore, that it is impossible at the present time to carry Cassagnau's scheme to its logical conclusion. From what we do know of the structure of the mouth parts of such genera as Pseudachorutes, Pseudachorudina, Micranurida, Holacanthella, and Ceratrimeria, I do not think that a classification at family and sub-family level of these forms could be based entirely on their mouth parts; these structures must be used in conjunction with other prominent body structures as I have indicated in the key suggested above. The sub-family Neanurinae is to me the most distinct of all these related sub-families, and on general morphological grounds alone I would hesitate to absorb this group into a large undifferentiated family along with such forms as Anurida, Pseudachorutes, and Ceratrimeria.

In 1948 and 1949, R. J. Bagnall erected in the Families Onychiuridae and Isotomidae a number of new genera which are not included in these keys. Many of these genera are of doubtful validity and will be dealt with in some special papers which I am at present preparing. On this account I have purposely omitted all these genera from these keys.