146 M. A. Giard on the Genus Entoniscus. 



so as to show the real form of the body, composed almost 

 exclusively of the ovary and the digestive tube. 



The incubatory chamber is composed of an anterior ventral 

 cavity communicating laterally with two latero-anterior cavi- 

 ties. Besides these three cavities, which are in communica- 

 tion, and form, so to speak, a trilobate cavity, the whole 

 dorsal part also presents a vast incubatory chamber, bilobed 

 posteriorly, and falling laterally in two folds, which meet 

 upon the ventral line when they are filled with ova. 



These various parts are more clearly visible in the animal 

 before it is completely transformed into the stage represented 

 by PI. X. figs. 3, 4 *. We then see distinctly the trilobed 

 ventral cavity and the two chitinous crests of the ventral 

 border of the dorsal chamber. 



This curious arrangement of the incubatory chambers is 

 very different from that indicated by Fritz Miiller in the case 

 of E. porcellance and E. cancrorum. The first of these two 

 species presents thoracic plates which only differ from the 

 ordinary plates of the Bopyridee by their much greater deve- 

 lopment and fringed appearance. The second certainly pre- 

 sents an anterior ventral incubatory chamber ; but this chamber 

 appears much more reduced than in E. Cavolinu, and does 

 not seem to communicate with the dorsal part of the para- 

 site. 



The terminal portion of Entoniscus, or that which corre- 

 sponds to the abdomen of the other Isopoda, is most frequently 

 recurved towards the ventral side of the parasite. At the 

 dorsal part of the first segment of this abdomen we see the 

 heart beating, which has never appeared to me to form a 

 hernia as in Entoniscus jjorcellance. 



The ventral portion of the abdomen bears five pairs of 

 folded and undulated lamellar appendages, corresponding to 

 the five pairs of ramified appendages of the abdomen in lone. 

 These appendages decrease in size from the origin of the 

 abdomen to the extremity of the body ; so that, apparently, 

 the first pair forms two large lateral tufts, and the last four 

 pairs a median posterior tuft, equivalent to each of the first 

 two. The last pair of appendages, however, are not very 

 visible, and are formed by a simple fold of skin on each side. 



The body terminates in a triangular expansion presenting 

 two dorsal folds. There does not appear to be an anus, which 

 is explained, as we shall see, by the arrangement of the diges- 

 tive tube. 



* These figures relate to E. Moniezii, but, for the point now before us, 

 they may equally apply to E. Cavolinii. 



