M. A. Giard on the Genus Entoniscus. 



1 E K 



loo 



The five pairs of abdominal feet are all constructed in the 

 same fashion : the basal joint bears one or two setse ; the 

 terminal setigerous joint presents a straight margin (fig. 10, a) 

 which bears two setas ; a third is inserted at the acute ex- 

 tremity. 



The only internal organs visible in the embryo are the 

 hepatic CEeca and the heart, which latter is seen beating 

 actively in the dorsal part of the first segment of the ab- 

 domen. 



In the following Table I summarize the characters of the 

 embryo of E. Cavolinn, compared with those of the species 

 described by Fritz Miiller : — 



E. PORCELLAN^. 



Length at hatching 

 0'2 millim. 



Frontal margin nearly 

 straight. 



Unpaired transparent 

 spot on the frontal mar- 

 gin. 



Inner margin of the 

 hand of the first five 

 pairs of feet smooth. 



Sixth pair of feet 

 short, three-jointed ; ter- 

 minal joint elliptical, 

 without a hook. 



Last segment of the 

 thorax wanting (?). 



Fifth pairofahdominnl 

 feet still hut little de- 

 veloped, destitute of 

 setse. 



Basal j oint of the ab- 

 dominal feet furnished 

 with a seta. 



Terminal joint of the 

 abdominal feet lancet- 

 shaped. 



E. CANCRORUM. 



Length at hatching 

 0-3 millim. 

 Frontal margin arched. 



No such spot. 



Inner margin of the 

 hand furnished with den- 

 ticles. 



Sixth pair of feet of 

 five joints, with a hand 

 furnished with a hook. 



Last segment of tho- 

 rax present. 



Fifth pair of abdomi- 

 nal feet present, like the 

 preceding ones. 



Basal joint of tbe ab- 

 dominal feet with two 

 setae. 



Setigerous joint 

 straightly truncate. 



E. Cavolinii. 



Length at hatching 



0*3 millim. 



Frontal margin nearly 

 straight. 



A median nauplian 

 eye on the frontal mar- 

 gin. 



Inner margin of the 

 hand furnished with two 

 teeth. 



Sixth pair of feet of 

 five joints, with a hand 

 furnished with a hook 

 and a rod. 



Last segment of tho- 

 rax present. 



Fifth pair of abdo- 

 minal feet like the pre- 

 ceding ones. 



Basal joint of the ab- 

 dominal feet with one 

 seta (?). 



Setigerous joint 

 straightly truncate. 



The larva3 of Entoniscus can live for several days in sea- 

 water. I have kept some alive that I had carried from the 

 Pouliguen to Paris, and from Paris to Lille. In ten days 

 they died without showing any modification. These embryos 

 swim in the position described by Fritz Miiller — that is to 

 say, with the body recurved towards the ventral surface, and 

 the sixth pair of thoracic feet projecting at the sides. 



I incline to think, however, that with these animals, as 

 with the other Bopyridae, copulation lakes place before the 

 commencement of parasitic life. In raosl [sopods the male is 



