ORDER ABDOMINALIA. 565 



whole thorax in Cryptophialus. I allude to this latter re- 

 semblance, for it was owing to it, and to the similarity in 

 the habits of Cryptophialus and Alcippe, that I stated, in 

 the introduction to my former volume on the Lepadidse, that 

 the two genera would probably fall into the same order. 

 In the structure of all the parts of the mouth and of the 

 cirri, in the digestive organs and in the metamorphoses, 

 Cryptophialus is not more closely related to Alcippe than to 

 any other genus whatever amongst the Lepadidee. 



Nevertheless I am confirmed in the view that the external 

 resemblances between these two genera are due to some 

 real affinity, and are not merely analogical, by a very re- 

 markable fact, — namely, that Alcippe and Cryptophialus 

 are both bisexual, and have males, several in number, at- 

 tached exactly in the same position, and which males are 

 so closely similar that, considered by themselves, they might 

 absolutely be almost classed as species of the same genus ! 

 For they agree in the absence of all internal organs and 

 parts, excepting the single testis, vesicula seminalis, and 

 immensely long probosciformed penis ; and they agree, also 

 in manner of growth, in the arrangement of the muscles, 

 and even in shape. The whole case seems to me very singular, 

 and, as far as my knowledge extends, unique : we have two 

 animals, of which the females, if classed by their external 

 parts (homologically consisting of the three anterior seg- 

 ments of the head), would be placed alongside each other 

 in the same family ; but when classed by the whole rest 

 of their organisation, certainly must be ranked in dis- 

 tinct orders;"* yet the males of these very same animals 

 might almost stand in the same genus. If it be asked 



* M. Milne Edwards would, perhaps, in accordance with the profound views 

 lately propounded by him on classification, consider Cryptophialus as an 

 extremely modified, and, to a certain extent, degraded member or satellite of 

 the type of the Lepadidae : but I do not myself feel able to draw a line of dis- 

 tinction between the being a very abnormal member of one group, and belonging 

 to a distinct group. I may add that I have several times tried to persuade 

 myself, with no success, into the belief that I have somehow misunderstood the 

 homologies of the thoracic segments and cirri of Alcippe and Cryptophialus ; 

 for if this were so, the two genera could be brought into much closer relation- 

 ship ; but with any conceivable amount of error on my part, there remains the 

 great difference in the metamorphosis, not to mention the palpable differences 

 in the cirri, the parts of the mouth, and in the whole course of the alimentary 

 canal. 



