ECTOPARASITIC TREMATODES. 279 



pore ; intestine with numerous lateral, bifurcating branches both 

 on the inner and outer sides, terminal portion without lateral 

 branches and projecting beyond the vitellarium, that of one side 

 slightly longer than the other. Common genital opening a little 

 in front of the hind end of the oesophagus ; genital atrium spacious, 

 armed with slightly recurved conical spines varying in length 

 from 13// to 16//. Ovary irregularly S-shaped in the dorsal as- 

 pect, presenting a convex border anteriorly, and with the 

 posterior end folded several times on itself. The oviduct arises on 

 the right side, and proceeding obliquely backwards and mediad 

 to near the front end of the testes, turns forwards and is conti- 

 nued into the ootyp ; no seminal receptacle was observed on its 

 course. Vitellaria almost completely enclosing the intestine and 

 its lateral branches, but leaving the front and hind ends free. 

 Paired yolk-ducts arising a little in front of the middle of the 

 body proper, uniting in the median line at the point corres- 

 ponding to the middle of the ovary ; the single yolk duct thence 

 proceeding posteriorly and opening into the oviduct close to where 

 the latter turns forwards to become the ootyp. Vaginal opening 

 dorsal and median, as much behind the posterior end of the 

 oesophagus as the common genital aperture is before it ; vaginal 

 canal long and dividing into two only at its hind end just before 

 opening into the paired yolk-ducts. Testes about 50, small, ex- 

 tending from the hind end of the ovary to near the hind end 

 of the body proper. 



Habitat. — Gills of blue-fish {Pomatomus saltatrix). 



Loc. — Newport, R. I. 



Microcotyle stenotomi n. sp. 

 (PI. XXI, fig. 28.) 



Body symmetrical, narrow, 2.5 mm. long, of which the 



