588 ORDER APODA. 



which cannot be thus explained. Proteolepas has no par- 

 ticular affinity to any other cirripede ; it resembles, indeed, 

 Cryptophialus in one important point, but only in one point, 

 namely, in the number of the segments of its body. It is 

 really beautiful to see how the homologies of the archetype 

 cirripede, as deduced from the metamorphoses of other cirri- 

 pedes, are plainly illustrated during the maturity of this 

 degraded creature, and are demonstrated to be identical with 

 those of the archetype Crustacean. I was at first inclined 

 to rank Proteolepas in one division, and all other cirripedes 

 in another division of equal value ; but as it may be inferred 

 from the characters of the prehensile antennae, that the pupa 

 did not differ much, if at all in any important character, from 

 the pupae of other cirripedes, I have thought the three orders, 

 which I have instituted, would be the most natural arrange- 

 ment. As any one looking at the drawing given of Pro- 

 teolepas, might very naturally feel inclined to protest against 

 its being ranked as a cirripede, I must reurge the import- 

 ance of the pupal antennae being constituted on the common 

 type, for from their structure, by the law of correlation, that 

 of the whole pupa may be inferred ; and even still more I 

 must insist on the importance of the one great character of 

 the antennae being cemented to the surface of attachment by 

 matter proceeding, as we shall see, in a modified state, from 

 the great ovarian sack. The structure, also, of the mouth 

 (to a certain extent), the segmentation of the body, though 

 in appearance so peculiar, the hermaphodite condition, the 

 single penis, the absence of oviducts, all accord with, and 

 taken together demonstrate, its cirripedial nature. 



