313] NORTH AMERICAN POLYSTOMIDAE—STUKKARD 33 



of the female duct where the vitello-vaginal canals are received and the 

 genito-intestinal canal is given off. The genito-intestinal canal twists 

 in a double loop and then opens into the intestine of the side upon 

 which the ovary is located (Fig. 10). The vaginae are ventro-lateral in 

 position and open to the exterior by funnel shaped mouths. The vitel- 

 laria occupy the dorsal and lateral regions of the body; they extend 

 anteriad to the pharynx and posteriad to the caudal disc. There is a 

 strand of follicles across the dorsal side of the body just behind the 

 pharynx, and then the follicles are entirely extracecal in the field ante- 

 rior to the testis; posterior to the testis the vitellaria overlie the ceca 

 and extend to the center altho they are scanty along the median line. 

 Ventrally the vitellaria are entirely extracecal. Collecting ducts run 

 longitudinally, laterad of the ceca; and just below the cecum of either 

 side the common vitelline ducts formed by the union of the anterior 

 and posterior longitudinal ducts unite with the internal ends of the 

 vaginae to form the vitello-vaginal canals. These canals open directly 

 into the ootype, one on either side, and are thus continuous, forming a 

 canal thru the body from side to side. Mehlis' gland is represented by 

 many nuclei which lie in the parenchyma around the ootype and uterine 

 duct. This latter duct passes anteriad and laterad on the opposite side 

 from the ovary ; it is smaller than the ootype in diameter and the epithe- 

 lial lining is lower. After a slight expansion it is constricted and then 

 opens into the uterus. The uterus contained a single egg or embryo. 

 Figure 14 shows a morula-like mass of cells found in one specimen ;• in 

 the other specimens there were large spherical eggs, each enclosed in a 

 yellow shell. They vary from 0.21 to 0.24 mm. in diameter. 



The excretory system shows no departure from the typical form 

 and while it can not be completely followed in sections, the larger ducts 

 occupy the characteristic positions. The descending collecting ducts 

 arise in the region of the anterior sucker and pass posteriad, lying lat- 

 eral and ventral to the ceca. They wind back and forth in short curves 

 and at the posterior end of the body turn anteriad and pass in the same 

 winding course to the excretory vesicles. Both descending and ascend- 

 ing ducts receive small branches at irregular intervals. The excretory 

 pores are lateral and dorsal, at the level of the bifurcation of the 

 intestine (Fig. 7). 



This species agrees with P. allnaudi in shape of caudal disc and 

 absence of great hooks, but differs from that species in type of uterus, 

 number of hooks in the genital coronet, and in the character of the 

 intestinal diverticula and testis. P. orbiculare agrees with P. hassalli 

 in the number of genital hooks, but the hooks are different in size and 

 shape ; P. hassalli has the great hooks of the caudal disc well developed 



