30/] XORTH AMERICAN POLYSTOM1DAE—STUNKARD 27 



Male Reproductive System. — The testis is a much branched structure 

 in P. kachugae; in P. integerrimum it is lobed, and in the other known 

 species it is oval or spherical. It is situated near or slightly anterior to 

 the middle of the body. A duct designated an internal vas deferens was 

 described in P. integerrimum by Zeller, but Ijima (1884) traced the true 

 relations of this tube and showed that it passes from the ootype to the in- 

 testine. Goto (1894) proposed the name canalis genito-intestinalis for 

 this structure which is discussed in a later section. The vas deferens 

 arises from the dorso-cephalic margin of the testis and passes dorsad and 

 anteriad. It extends dorsal to the ootype, between the dorsal margins of 

 the ovary and uterus to the level of the genital pore where it turns ven- 

 trad and enlarges to form the seminal vesicle (Fig. 13). From the semi- 

 nal vesicle a duct passes thru the cirrus sac, opening into the genital 

 atrium (Fig. 26). The vas deferens is small and has a fibro-membran- 

 ous wall, and the seminal vesicle has a lining of columnar epithelium. 

 The cirrus sac is composed of an external muscular wall enclosing a mass 

 of parenchymous tissue which surrounds the ejaculatory duct. This sac 

 is very small in P. integerrimum and P. hassalli. Ventrally it opens into 

 a common genital atrium (Fig. 26). The ejaculatory duct terminates in 

 the genital papilla, which when retracted is surrounded by a deep depres- 

 sion. In the musculature between this depression and the wall of the 

 cirrus sac are embedded the roots of the genital hooks. "When the hooks 

 are retracted there is a shallow depression between them and the wall of 

 the sac. "With the contraction of the wall of the cirrus sac the genital 

 papilla and the circle of genital hooks are extruded thru the pore. In 

 most of the species the hooks are sickle shaped with the points project- 

 ing outward, and with muscles attached to the outside of the hook at the 

 juncture of the root and shank. These muscles undoubtedly serve as a 

 fulcrum, and the extrusion of the papilla rolls the hooks outward bury- 

 ing their points in the cuticula lining the Avail of the vagina of the copu- 

 lating worm (Fig. 24). In P. alluaudi Beauchamp described three 

 genital hooks, P. integerrimum has eight, and other species sixteen, 

 thirty-two, and forty. In P. hassalli the genital hooks are small, straight 

 and have a wing like process at the middle. 



Zeller described a prostate gland in P. integerrimum, consisting of 

 masses of large cells situated around the cirrus, and traced ducts from 

 these cells to the lumen of the ejaculatory duct. Johnston in P. bullienst 

 says, "Two laterally placed, small groups of gland cells represent the 

 prostate." The statement of Zeller that a gland is present around the 

 cirrus of P. integerrimum is certainly correct. In the species described 

 in this paper, a similar gland is present in the parenchyma around the 

 genital sinus. The cells (Fig. 12) are globular or pyriform, stain deeply 



