142 ILLINOIS BIOLOGICAL MONOGRAPHS [142 



cirrus-pouch is situated. The cirrus-pouch (Figs. 47, 48, 49) is very- 

 short, reaching just a little way through the vitellaria. Its length is 

 about 0.160 mm. making the ratio of its length to the proglottid breadth 

 about 1 :6 to 1 :8. The cirrus-pouch is bent up toward the inner dorsal 

 wall of the dermo-muscular sac. Within the cirrus-pouch the ductus 

 ejaculatorius forms but one or two coils before passing over into the 

 short, but thick-walled cirrus. The cirrus is straight, ft was not pro- 

 truded in any specimens examined by the writer. 



The vagina lies anterior to the cirrus-pouch, but the opening of 

 the vagina into the genital atrium is situated almost dorsal to that of 

 the cirrus (Fig. 48). Very near the opening of the vagina there is a 

 weak sphincter vaginae. The lumen of the vagina in its initial region 

 is quite lai^. This however soon constricts and the remainder of the 

 vagina is of small diameter. The drawings (Figs. 47, 48) show how the 

 vagina which opens anterior and dorsal to the cirrus-pouch passes over 

 the latter in its course to the ventral surface and then backward to the 

 ovary. Several species of Proteocephalus, e. g., P. percae, P. pinguis, 

 and P. exiguus show this twisting of the vagina part way round the 

 cirrus-pouch. This point has not been investigated in many species but 

 it seems probable that it is quite a constant character of the genus. 



The broadened region of the vagina bears a ciliated lining on its 

 inner surface but the presence of the cilia could not be demonstrated 

 throughout the length of the vagina. A small receptaculum seminis 

 was found a little way anterior to the mid-piece of the ovary. The 

 ovary (Fig. 49) is a heavj' bilobed structure of much the same shape as 

 in P. percae or P. cernuae tho shorter in those species. The viteUaria 

 are long follicular ma^es iii the lateral fields- of the proglottids. The 

 follicles are closely compacted. An oocapt possessing a heavy muscula- 

 ture is present, also an oot}i)e with its surrounding shellgland. 



The uterus (Fig. 47) in ripe proglottids is made up of a median 

 tube with 7-11-12-14 lateral outpocketings on either side. The septa 

 between the uterine pouches are sometimes very thin and in other cases 

 quite thick. The uterine passage is a small tube which after a sinuous 

 course empties into the uterus about the middle of the proglottid. The 

 uterine openings are 1-2 in number. Schneider in his specimens found 

 only a single uterine pore. In reality this difference between the find- 

 ings of Schneider and the writer is slight and too inadequate to serve 

 as a basis for a specific distinction- A second uterine pore is very read- 

 ily overlooked. Especially is this true in some species in which the 

 second pore when present is smaller than the first and is situated some 

 distance from it. The eggs were taken from the uterus of alcoholic 

 specimens. The thin outer hyaline shell, characteristic of the e^s of 



