The Nauplii of Notodelphys agilis Thorell and Doropygus porcicauda Brady

Extract

The Notodelphoidea are a heterogeneous collection of copepods which are found parasitic within urochordates and there is considerable doubt as to the exact systematic position which should be occupied by this group. It comprises—in the sense in which it is used by Sars (1921)—six families of excessively doubtful affinities in that there are grouped together Copepods (1) which brood their eggs (Notodelphys, Doropygus, etc.), (2) others which are possessed of elongate egg-strings (Entericola), (3) and others which deposit their eggs singly (Mycophilus). Now it appears to the present writer that such great variation in habit must argue an equally great variation in the structure of the genital organs, for the “cement gland” and “hardening gland” (see Gray, 1928) may be presumed to be absent if egg-strings are not formed. It is doubtful, therefore, whether any useful discussion on the classification of these forms can take place without a parallel and detailed investigation of the internal anatomy. There is, however, another line of approach—the study of larval forms. It is equally as a preliminary skirmish along this line of attack, and as a contribution to our knowledge of larval forms, that the present brief note is presented.