LIFE-HISTORY OF BUCKPHALUS HAIMEANUS. 667 
usually spindle-shaped, are seen more easily than in Buce- 
phalus. The distribution of nerves is much the same, a 
number passing forward and two main stems passing later- 
ally and ventrally, innervating the pharynx and the posterior 
part of the body. 
THe Warer VASCULAR SYSTEM. 
In but a few of the living Gasterostoma, which I have 
studied, have I been able to make out any trace of the excre- 
tory system. In the few fortunate instances I have observed 
scattered flame cells and the outline of the end bladder. In 
no case have I seen the bladder contract. 
Longitudinal sections show that the sac opens to the ex- 
terior through an excretory pore which is situated at the 
posterior end of the body near the dorsal surface (fig. 56). 
The duct connecting the water vascular sac with the exterior 
is short and surrounded by large sphincter muscles. 
THe GENITAL ORGANS. 
The reproductive organs, of which only the rudiment was 
present in Bucephalus, had reached their full development in 
most of the Gasterostoma which I have examined. The 
arrangement is that of the typical Trematode (figs. 46 and 
47). 
FEMALE REPRODUCTIVE ORGANS. 
The ovary is situated a little to the right of the median 
line, slightly anterior to the middle of the body. It is oval 
in outline, slightly longer than broad, with its long axis 
parallel to the long axis of the body (fig. 52). 
From its posterior end it gives off an oviduct which widens 
into a flask-shaped enlargement. At the posterior end of this 
enlargement Laurer’s canal originates. This passes through 
a convoluted course to open on the dorsal surface of the 
body. After leaving the enlargement (seminal receptacle) 
