272 SCALPELLUM PERONII. 



a small tuft of fine bristles ; width '001 of an inch, and 

 therefore only -^th of the size of the same organ in the 

 hermaphrodite : the relative sizes of the maxillaB and 

 mandibles are the same in the male and hermaphrodite. 



Outer Maxilla blunt, triangular, with a few thinly- 

 scattered bristles on the inner face ; those on the out- 

 side being longer. 



Cirri. — The First pair is far removed from the second ; 

 the rami are very short, barely exceeding the pedicel 

 in length ; they are formed of only four segments, each 

 bearing a pair of spines ; but on the end of the terminal 

 segment, there are three spines, of which the central 

 one is very long. Second pair also short. In the sixth 

 pair there are five or six elongated segments, each bearing 

 three pair of long spines ; dorsal tufts large. The cirri 

 are furnished with transversely-striated muscles. 



The Caudal Ajopendages exist as two very minute plates, 

 with a few bristles at their apices. 



The Penis is not acuminated, with four bristles at the 

 end ; it is short, equalling only the lower segment of the 

 pedicel of the sixth cirrus. In the one specimen pre- 

 served in spirits, I unfortunately omitted to search for the 

 vesiculae seminales ; I cannot doubt that such existed, but 

 it would have been important to have ascertained whether 

 they contained spermatozoa. I made out, most distinctly, 

 that there was no trace of ovarian tubes within the pedun- 

 cle ; and my assertion may be believed when I state, that I 

 traced the two much finer and more transparent cement- 

 ducts, from the prehensile antennae up to the body of the 

 animal : in Lepas I have repeatedly detected, with ease, 

 the ovarian tubes within the peduncle, before the calcifi- 

 cation of the valves had even commenced, and therefore 

 at a much earlier period of growth than in these parasites. 

 Consequently I am prepared to affirm, that these parasites 

 are not females, but that, as far as can be judged from 

 external organs, they are exclusively males. 



Concluding Remarks. — In comparing the capitulum of 

 the hermaphrodite with that of the complemental male 



