356 



at the attached end of its peduncle, and in many cases afford import- 

 ant characters for zoological discrimination. 



The knowledge thus gained from the study of development is 

 most sagaciously and happily applied by you to explain the homo- 

 logical relations between the Cirripeds and Crustaceans ; and in this 

 way you have conclusively shown that the peduncle of the mature 

 Lepad corresponds with the three anterior segments of the Crusta- 

 cean. Again, by your discovery of Proteolepas, a new parasitic 

 Cirriped of low organization, you have been able successfully to 

 compare the remaining segments of the body in the two classes; for 

 whilst the chain of evidence is in some measure broken by the 

 absence of two segments near the middle of the series in Cirripeds 

 generally, the missing links are supplied by the newly- discovered 

 animal referred to. 



The existence of an eye with a pair of ophthalmic ganglia in adult 

 Lepads, as had been previously shown in Balanids, — the presence too 

 of organs seemingly intended for hearing and smelling — the chemical 

 nature of the tegumentary coverings — the cement-gland and ducts, 

 yielding a plastic material for attaching the peduncle and for other 

 special purposes in particular instances, and the singular organic 

 connexion between that gland and the ovaries, are all most interest- 

 ing discoveries in comparative anatomy, first made known in your 

 work. 



Some very singular facts respecting the reproductive function in 

 the Lepadidce have been brought to light through your researches. 

 You observed that the ova, on leaving the ovary, are gathered in a 

 layer underneath the internal lining of the sac or mantle, from 

 whence they are freed and extruded by the process of moulting, and 

 then form the ovigerous lamellae already known. Again, you have 

 clearly established, that, contrary to the hitherto received opinion, 

 there are species of Lepadidse consisting of individuals of distinct 

 sexes, the male being parasitic on the female ; and in certain other 

 species you have discovered a condition hitherto unknown in the 

 animal kingdom, namely, bisexual individuals impregnated by 

 parasites simply of the male sex, which you name " complemental 

 males," — a fact unquestionably of first-rate interest in relation to 

 the physiology of the reproductive function in general. 



Besides these more important observations, there are many more 

 of lesser mark to be met with in the descriptions of particular 

 species, — descriptions, it may be observed, which are founded on a 

 careful examination, not only of the external characters^ but of the 

 internal structure of the animals in question, in specimens obtained 

 from every available source, both at home and abroad ; and the 

 zoological distinctions are rendered more precise and intelligible 

 than heretofore, by the introduction of a consistent and philoso- 

 phical nomenclature. 



