01RRJPEDIA ABD0M1NALIA. 563 



diversity of nature, even in the same sub-class, I may be 

 permitted to remark, that whilst in Alcippe only the three 

 anterior segments are developed, the fourteen succeeding 

 segments being rudimentary, in Proteolepas (hereafter to be 

 described) these fourteen segments are all largely developed, 

 whilst the three anterior segments are quite aborted, being 

 represented only by a thin envelope to the two threads by 

 which this Cirripede is attached to the supporting object. 



* 



Order IT. — Cirripedia Abdominalia. 



Cirripedia, having a flask- shaped carapace ; body consist- 

 ing of one cephalic, seven thoracic, and three abdominal 

 segments; the latter bearing three pairs of cirri ; the tho- 

 racic segments without limbs ; mouth with the labrum 

 greatly produced, and capable of independent movements ; 

 oesophagus armed with teeth at its lower end ; larva, firstly 

 egg-like, ivithowt external limbs or an eye ; lastly binocular, 

 without thoracic legs, but ivith abdominal appendages. 



I feel compelled to form an Order for the one genus and 

 species, namely, Cryptophialus minutus, to be here described. 

 We must, I conceive, attribute much greater value, in classi- 

 fication, to internal parts and organs, at least where such 

 are not known to vary, than to external structure. Now in 

 Cryptophialus, the body consists of eight segments, of which 

 the first two are not developed in any cirripede hitherto 

 described. Of the eight, the seven posterior or thoracic 

 segments are quite free, or detached from the carapace, and 

 do not bear any appendages ; whereas in all the foregoing 

 cirripedes of the order Thoracica there are (at least in the 

 normal sex) six pairs of cirri ; Alcippe alone must be ex- 

 cepted, in which there are only two pairs. Again, in the 

 Thoracica there are no abdominal appendages, excepting 

 the terminal or caudal, whereas in Cryptophialus the ab- 

 domen bears three pairs of biramous cirri. In the crest of 



* It may be worth stating, that in order to procure perfect specimens of the 

 female and male Alcippe, pieces of the shell inhabited by them should be dis- 

 solved in weak acids. 



