506 ON TWO REMARKABLE SPOROCYSTS, 



ponding main excretory vessel, right or left as the case ma}^ be. 

 Each of these runs outwards and forwards to a point near the 

 margin of the body, where it divides into an anterior and a 

 posterior longitudinal trunk. The ciliated funnels are 0-0075 mm. 

 in diameter. There are always twelve of them in mature Cercariae, 

 and their arrangement is quite constant. One funnel terminates 

 each of the anterior and posterior longitudinal vessels ; the 

 remainder are situated at the ends of longer or shorter side- 

 branches in the way shown in fig. 10. 



No funnels and no vessels were observed in the tail. In this 

 respect this Cercaria differs apparently from other described 

 forms. Wagener (17) states that in the Cercariee with forked tail 

 the excretory bladder extends into the tail and becomes bifurcate, 

 each branch opening at the end of the corresponding branch of 

 the tail; and Loos (7) describes and figures the extension into the 

 tail of the main excretory vessel in the Cercaria? of Amphistomum 

 suhclavatum. 



The reproductive system is fairly well advanced in the mature 

 Cercaria. The ovary is a rounded mass of cells situated a little 

 behind the point of bifurcation of the intestine. From it the 

 oviduct proceeds as a narrow tube which runs forwards and 

 towards the left passing on the ventral side of the left ramus 

 of the intestine, and bending in again tow^ards the middle line to 

 open at the genital aperture immediately in front of the ventral 

 sucker. A rounded mass surrounding the oviduct shortly after 

 it leaves the ovary is evidently the shell-gland. The rudiments 

 of the testes are two small oval bodies situated between the rami 

 of the intestine some distance behind the ovary. The vitelline 

 glands are not yet distinguishable. A rounded bod}^ dorsal to 

 the anterior part of the ventral sucker is probably the vesicula 

 seminalis. 



In the form and arrangement of the spines around the anterior 

 end, the series of lateral ridges in the region immediately follow- 

 ing, and the form of the phar3mx, this Cercaria resembles the 

 adult Distomum fasciatum, Rud., and probably is the larva of a 



