ECTOPARASITIC TREMATODES 269 



the oviduct directly behind the ootyp ; but in the present species 

 the latter lies at a considerable distance forwards, about half 

 way between the openings of the shell glands and the opening of 

 the uterus into the genital atrium. The latter is a slender canal- 

 like cavity and is expanded only at its posterior end, where it 

 contains the joeuis. 



Epibdella sciœnœ P. J. v. Beneden. 



The following notes on this species are based on a single 

 mounted specimen in possession of Dr. Stiles of Washington, who 

 has kindly permitted me to study it. The specimen is stated to 

 have come from Dr. P. Sonsino of Pisa and to have been found 

 on Sciœna umbra. 



The specimen (fig. 8) is very small, being only 13 mm. 

 long, but the genital organs appear to be mature, as the vas 

 deferens and the seminal receptacle are filled with sperma- 

 tozoa. 



As stated under the foregoing species, the genus Epibdella is 

 distinguished from it by the possession of well developed anterior 

 suckers. These are circular in the present species and are roughly 

 one third as large as the posterior sucker in diameter. The latter 

 is armed with three pairs of hooks, which have been well described 

 by van Beneden ['61]. The most anterior piece (fig. 9) is consid- 

 erably larger and stouter than the others, and is 0.72 mm. long ; 

 its posterior end is bifurcated, and at its middle it has a broad tri- 

 angular process on one side, which is directly continued into one 

 of the branches of the bifurcation. The middle piece, as measured 

 on my specimen, is 0.30 mm. long ; but I suspect that its posterior 

 portion is wanting. The most posterior piece is provided with a 

 very distinct hook at its hind end. The anterior portion is lamellar 



