No. 3.] CLINOSTOMUM HETEROSTOMUM. 703 



dilated receives the oviduct, which has curved on itself and 

 now runs backward and downward. The dilatation contains 

 yolk-granules, spermatozoa, and occasional ova, and is continued 

 into a third ciliated canal which runs forward and upward to 

 open dorsally into the median line by a circular aperture. This 

 is Laurer's canal. 



The walls of the first dilatation of the uterine tube are very 

 mobile, and may be considered to form an ootyp as the egg 

 there receives the shell. It is surrounded by a number of large 

 cells with large round nucleus and nucleolus, and deeply stain- 

 ing granular protoplasm which probably function as a shell 

 gland, although such a relation could not be directly deter- 

 mined. 



In many specimens the proximal portion of the uterine tube 

 contains great numbers of spermatozoa which lie in the inter- 

 stices between the eggs. The uterine tube is rather thin-walled 

 and short, and after making a few convolutions in the area 

 between the testes it runs forward to join at its left posterior 

 angle the large quadrangular sac, which forms, when full of eggs, 

 so conspicuous a feature in the living worm. The walls of the 

 sac, which occupies the whole space between the acetabulum 

 and the anterior testis, and the intestinal coeca laterally, are 

 rather thicker than those of the uterus proper. They are like 

 the rest of the uterine wall, underlaid by a layer of deeply 

 staining cells, probably of a secretory nature. At its posterior 

 end, directly in front of the anterior testis, this sac passes by a 

 sphinctered opening into a muscular bulb-like vestibule, which 

 opens again in the median line ventrally by the elongated 

 sphinctered external orifice which lies directly in front of the 

 male genital pore {PI. XXXIX, Fig. 3). 



The connections of these various ducts is made plain by the 

 figure (PI. XXXIX, Fig. 2) and need not be further described. 

 I have not been able to make out any trace of a receptaculum 

 seminis such as is described by Wright. 



The eggs are large and numerous, and are provided with a 

 thick shell and a well-marked operculum. 



I have before me, through the kindness of Dr. Hassall, the 

 type specimens of two forms which, as he has suggested, are 



