68 ILLINOIS BIOLOGICAL MONOGRAPHS (348 



cross sections each 15/i in thiqlmess, and the tube is so coiled that in a 

 section of the worm there are ten or fifteen sections of the vesicle. In an- 

 other individual cut in frontal sections the seminal vesicle extends antero- 

 posteriorly thru 0.57 mm. The prostate gland is enclosed by the cirrus 

 sac and fills the entire region between the wall and the central canal. 

 The cells are more numerous in the posterior part of the sac, gradually 

 becoming fewer in the anterior region. The sac is approximately 0.37 

 mm. long and 0.185 mm. in diameter. It is dorsal on the right side of 

 the body, and the terminal end of the uterus is ventral on the left side 

 of the body. 



Female Reproductive Organs. — The ovary is spherical or oval, 0.275 

 to 0.35 mm. in length and 0.33 to 0.57 mm. in width, in or near the me- 

 dian line, about the width of the caudal testis behind the latter. The 

 oviduct is very small and arises from the dorsal margin of the ovary (Fig. 

 61). After a coil posteriad Laurer's canal is given off and passes in a 

 winding course to the dorsal surface. There is no receptaculum seminis. 

 Just after the origin of Laurer's canal, the oviduct passes into ilehlis' 

 gland, where the vitelline duct is received. There is no vitelline re- 

 ceptacle in either of the sectioned worms, but the right and left ducts are 

 very large. They meet in the median line posterior and ventral to 

 Mehlis' gland, and a duct passes to the ootype. The uterus coils an- 

 teriad, either between or around the testes and opens thru the hermaphro- 

 ditic duct to the genital pore. 



The genital pore is in the median line ventral to the esophageal bulb, 

 and there is a small genital sinus. The cirrus sac and metraterraal por- 

 tion of the uterus open to the exterior thru a common hermaphroditic 

 duct (Fig. 60). 



The viteUaria consist of smaU irregularly shaped follicles, lying al- 

 most entirely in the ventral half of the body and extending from the re- 

 gion of the cephalic testis to the caudal ends of the ceca. Anteriorly 

 they are extracecal, but posteriorly they extend into the intracecal area ; 

 near the ends of the ceca about half of the follicles are between the di- 

 verticida. 



Eggs were present in only one specimen. Here there were three; 

 they measured 0.1 by 0.13 mm. 



Lymph System. — This system consists of three canals passing long- 

 itudinally on either side of the body, one lateral and two mesal of each 

 cecum. Of the median pair, one is dorsal and the other ventral (Fig. 

 59). These canals are not straight but wind about and give off branches 

 at various points. These branches subdivide in turn and at the ends the 

 main trunk breaks up into numerous smaller branches so that the entire 

 body is penetrated by ramifications of this system. The ceca, the genital 



