1.—PERMANENT PLANKTON

The species comprising this first section are present in their adult form all the year round and numbers do not fluctuate significantly during the year. These include Isopoda, Amphipoda, Gopepoda, and Chaetognatha.

Small numbers of Isopoda occur but these have not received any special attention.

Amphipoda (Hyperiidae) of several species occur in the majority of samples, but these are rare in all months of the year (Text-fig. 7).

Copepoda are the most plentiful component of the permanent plankton, and many species are present in the Wellington area. Copepoda are particularly significant in the winter months (June, July, August) when other crustacean species are comparatively scarce (Text-fig. 7). Parasitic Gopepoda (Galigidae) mainly male have been taken only rarely.

The arrow worm Sagitta serratodentata var. tasmanica Thomson, is found in the majority of samples throughout the year, but it is never numerically significant (Text-fig. 7). This species is considered to be of oceanic origin, as greater numbers occurred in samples taken during a flooding tide.