85 



of this uncertainty are partly, that the males of too few forms are known, partly — and 

 particularly — that the metamorphosis of numerous genera among the old families and of 

 the more abnormal forms is entirely unknown, and that the structure of the mouth in the 

 adults as well as in the larvae is often badly studied, etc. A revision of the classification 

 of the parasitic Copepoda would be most desirable and ought to be based upon a thorough 

 study of the external structure of both sexes, and upon numerous new data which throw light 

 on the post-embryonic development ; that a representation of the internal structure of numerous 

 types would be excellent, goes without saying, but even without undertaking this gigantic 

 work such a revision as the above-mentioned would be exceedingly useful. However, as 

 such a work does not exist, I do not see that it can be of much use to discuss the relation- 

 ship of the Choniostomatidae and their place in the system more in detail, so I will content 

 myself with some few remarks. 



The last detailed systematic arrangement of the parasitic Copepoda was undertaken 

 by A. Gterstaeckek in »Bronn's Klassen und Ordn. des Thier-Reichs, fiinfter Band, erste 

 Abth.« p. 721 — 729, and this part was published about 1870. Perhaps we might also 

 mention the more condensed grouping in »C. Claus: Grundsiige der Zoologie, B. I, 1880, 

 p. 554 — 58, « as it is set up by the author who has also gained great distinction in this 

 domain of carcinology. By studying these treatments and several papers on special groups, 

 I have found out that the family Choniostomatidae stands far apart from all hitherto established 

 families, except Lernaeopodidae, from which, however, it also differs considerably. If Salensky 

 in his often mentioned paper means that Sphceronella comes nearest to Lernaeidae, because he 

 thinks that in the structure of the mouth and in the form and position of the maxillae and 

 the maxillipeds, it resembles Lemma branehialis in the pairing stage, we admit indeed that 

 the resemblance in the structure of the mouth is doubtless very striking, but in other respects 

 the various larval stages of Lerncea and Pennella differ widely from the larvae and pupae of 

 Choniostomatidae, and the subsequent development of the two genera of Lernaeidae, as we 

 know, differs so thoroughly from that of the Choniostomatidae, moreover, the structure and 

 egg-laying of the female of Lerncea is so exceedingly different from these features in our 

 family, that a closer relationship is entirely out of the question: in my opinion Lernaeidae 

 and Choniostomatidae stand very far from each other. But undeniably it stands even farther 

 apart from Herpyllobiidae, though Giard and Bonnier have attempted to unite it with this 

 most remarkable family, which differs widely from all other parasitic Copepoda. They do so 

 by establishing a new family: Sphaeronellidae, which they subdivide into Choniostomatinae 

 and Herpyllobiinae. Tins peculiar classification I have criticised at length in my general 

 historical view (p. 15 — 21), to which I refer. The same two authors, in their earlier work, 

 published in 1889, say that Choniostomatidae comes nearest to Chondracanthidae, Lernaeopodidae 

 and Ascomyzontidse. The first and the last of the families in several respects — e. g. in 

 the structure of the mouth — deviate so much from Choniostomatidae, that any closer 

 relationship is out of the question; indeed our family stands widely apart from both, 



