333] XORTH AMERICAS ASPIDOCASTRIDAE—STrXKARD 53 



nuclei lying in the parenchyma around the ootype. The uterus passes 

 posteriad on the lateral side of the collecting duct of the excretory 

 system as far as the caudal end of the testis where it turns to the median 

 line. It passes ventrad and anteriad beneath the testis ; in fi'ont of the 

 testis it turns dorsad and toward the ovarj', but just before reaching 

 the ovary it turns and crosses to the opposite side of the body and then 

 passes with little deviation to the genital pore. There is a strong sphinc- 

 ter at the distal end of the uterus (Fig. 54). Eggs were present at 

 various places in the course of the uterus and when the worms were 

 placed in tap water, the eggs near the pore were extruded. The eggs 

 are few in number, not more than six being present in any specimen. 

 They vary from 0.071 to 0.086 mm. in width and from 0.137 to 0.14") 

 mm. in length. The average of twenty-five is 0.075 by 0.141 mm. 



The vitellaria (Figs. 46, 49) are arranged along the sides of the 

 body, extending from the posterior end to the level of the cirrus sac. 

 The follicles are more numerous and closer together in the posterior 

 region, gradually becoming fewer in the anterior part of the vitelline 

 zone. They lie just above the limiting membrane which forms the 

 dorsal boundary of the musculature of the adhesive disc, and number 

 up to forty on each side. They vary in size, measuring from 10 to 40/x 

 in diameter. In some specimens they appear to be arranged in a double 

 row on each side with the follicles placed alternately, but there is com- 

 mon and wide variation from this condition. Collecting ducts extend 

 along the median face of the vitellaria and at the level of the ootype 

 pass mediad where they unite to form a small receptacle which empties 

 into the ootype. In C. cokeri the vitelline follicles are smaller and fewer 

 in number than in C. insignis. 



The genital pore (Fig. 54) is double, situated in the median line 

 on the ventral side of the forebody, dorsal and anterior to the adhesive 

 disc. There is no genital atrium, the two diiets open to the exterior 

 separately, the opening of the cirrus sac is on the right and that of the 

 metraterm is on the left. Barker and Parsons described a genital atrium 

 opening thru a common pore, but I fail to find such a structure. In 

 C. insignis, Osborn described a single genital opening and a genital 

 atrium, but in sections of C. insignis I find the same condition as in 

 C. cokeri. 



Excretory Sysicm-. — ilost of the observations on this system were 

 made on living specimens. As the water evaporated from under the 

 coverglass the worm was flattened and the larger excretory tubules 

 could be easily followed. The pore (Fig. 50) is median, dorsal, near 

 the posterior end of the body. There may or may not be a small papilla- 

 like prominence around the pore. There is a single excretory vesicle, 



