38 ILLINOIS BIOLOGICAL MONOGRAPHS [318 



i 



lining 0.017 to 0.035 mm. in thickness set upon a fibro-membranous base. 

 The vitellaria are so thick that the diverticula can not be traced in toto 

 preparations. 



The testis is situated near the center of the body; it is spherical 

 or oval, 0.28 to 0.33 mm. long, 0.33 to 0.38 mm. wide, and in the sec- 

 tioned worm 0.28 mm. thick. "The course of the vas deferens and the 

 character of the male organs are similar to those in the previously 

 described species. The genital coronet contains thirty-six hooks in one 

 and forty-two in the other toto preparation. They are similar in size 

 and shape, have a straight basal portion with bifid end which is embedded 

 in the wall of the cirrus sac, and a sickle shaped shank which projects 

 into the genital atrium. The basal portion is the same length as the 

 shank and each part measures 0.03 mm. 



The ovary (Fig. 23) is a broad comma-shaped organ, situated about 

 midway between the pharynx and testis, on either side of the body. 

 The larger part is anterior and ventral and contains many nuclei of 

 forming ova, and there are zones of developing ova, each with larger 

 and fewer cells until dorsally and posteriorly the oviduct is given off. 

 The oviduct passes mediad, expanding slightly, and then posteriad and 

 ventrad to open into the ootype. This structure is in the ventral part 

 of the body, just anterior to the testis (Fig. 24) ; from the sides it de- 

 ceives the vitello-vaginal canals and gives off the genito-intestinal canal. 

 This canal after winding in a double loop opens into the intestine on the 

 same side as the ovary. It was empty in the sectioned worm. The 

 external openings of the vaginae are situated on small prominences 

 ventro-lateral in position, altho there is a single large opening to the 

 exterior. The vitellaria consist of masses of follicles occupying the dor- 

 sal and lateral areas of the body. They form a sheet of gland cells on 

 the dorsal side of the body posterior to the testis. They are somewhat 

 reduced along the median dorsal area in the anterior half of the worm 

 and entirely absent only in small fields over the testis and uterus. They 

 extend along the sides of the body and ventrally are limited by the ceca. 

 On either side, at the level of the ootype, a common duct from the longi- 

 tudinal collecting ducts passes ventrad and just below the cecum unites 

 with the vagina of that side to form the vitello-vaginal canal which 

 discharges into the ootype. The uterine duct leads to the uterus, which 

 in each of the specimens contained a large egg. A section of the egg is 

 shown in Figure 23. The eggs are oval, 0.15 by 0.18 mm., and in the 

 sectioned worm the egg is 0.24 mm. in thickness. From the uterus a 

 small duct passes anteriad and ventrad, opening into the genital atrium, 

 posterior and ventral to the cirrus sac. 



The excretory system agrees with the general description given. 



