592 General Notes. LJ ul y> 



site is not at all pigmented. The position of the latter is exactly 

 the same as in Bopyrus, the dorsal side being directed toward the 

 gills of the host and the ventral side toward the swollen carapace 

 of the same. 



The examination of our parasite revealed an isopod crustacean 

 belonging to the sub-genus Bopyroides established by Dr. Win. 

 Stimpson, 1 being closely allied to both the genus Bopyrus and 



Gyg6 - 2 . . mm 



The female of our parasite measures if™ in length and l 

 across its widest diameter. It is not as flat but more of a globu- 

 lar shape than Bopyrus, its integument also less chitinized, the 

 whole body therefore softer. The body is unsymmetrical in shape, 

 similar to Bopyrus, differing also in this respect from the genus 

 Gyge, which is unsymmetrical anteriorly only. Dorsally the seg- 

 ments of the pleon, or tail, are distinct, whereas in Bopyrus they 

 are fused or connate in the central dorsal axis. In this respect it 

 agrees with Gyge as well as in some respects concerning the form 

 of the gills. The latter do not consist of short, thick, fleshy, 

 transversely placed lobes, but of fleshy, roundish ridges attached 

 within the ventral lateral extremity of the six segments of the 

 pleon. 



Seven pairs of legs (pereiopods) are developed on one side and 

 only one pair on the opposite side, the remaining six being obso- 

 lete through parasitism. They are similar to those of Bopyrus 

 palcem., but even less distinct and not pigmented centrally. The 

 side having but one leg is curved outward. 



The marsupium or breeding cavity is bounded posteriorly by 

 the transverse prolonged lamella of the last pereiopod, anteriorly 

 by the cephalic pi. i ■ and th i im. li:e of the first pair of pereio- 

 pods, laterally on one side by the fleshy longitudinal ridge along 

 the other developed pereiopods, which are, if I see rightly, there 

 without lamellae. On the opposite side, where only the first 

 pereiopod remained, the marsupium is covered by two fleshy, 

 sparsely pigmented lamellae (Figs, i and 2 a, a), and three or four 

 very thin and delicate broad membranes (Figs. 1 and 2 b). The 

 membranes and lamellae are evidently the prolonged margins ot 

 the thoracic segments. 



The eggs measure 0.i2 m,n in diameter. There are scarcely 

 more than sixty eggs in some marsupia, the greater part of mar- 

 supia containing bTt a few eggs. On account of the scarcity ot 

 material but little was don : to study the eggs; they were all in 

 the earlier stages of development, without any pigmentation and 

 of a yellowish color. 



The cephalic portion, or head, consists apparently of but one 

 triangular fleshy piece. I was somewhat surprised to find in tne 



V »rS) S§Ll Ja ,„a p„o„ p,_: :„ vr_ i»A 0-.1, M Torino. Ser. 2, Tom. 



