30 ILLINOIS BIOLOGICAL MONOGRAPHS [380 



The genital cloaca could not be studied as carefully as desired, on 

 account of its habit of turning inside out at the approach of sexual 

 maturity. A full comparison of the organ with that of Schizotaenia 

 anoplocephaloides, to be described later, is therefore not possible. They 

 agree however in all points that could be made out. In both the cloaca 

 everts at the approach of sexual maturity ; and in both it is drawn back 

 at the close of sexual activity, but in none of the sectioned material at 

 hand does it come back completely. In both the cloaca is very large 

 tho in the present species it is not so extraordinarily large as in the 

 other. The proglottids sectioned do not show whether the cloaca is 

 divided into two parts, as in S. anoplocephaloides. The pore is located 

 about midway on the margin. 



The cirrus pouch is quite large, tho small as compared with that 

 of 8. anoplocephaloides. When the cloaca is not everted, about a third 

 of it lies mediad of the excretory ducts ; when everted it reaches usually 

 just to the nerve trunk. It is 500-625/* long by 185-210/* wide. It is 

 somewhat pear-shaped in outline, the inner half being about uniform in 

 diameter. Laterad of the middle it tapers sharply to end in a slender 

 neck 40/* in diameter and 150//. long. The cirrus is spiny. Extruded 

 cirri however are smooth, from which it would seem that the attachment 

 of the hooks is very light. This probably explains the apparent absence 

 of spines observed by Stiles for 8. americana leporis. The inner end 

 of the cirrus pouch is occupied by a portion of the vesicula seminalis. 

 Outside the cirrus pouch the vesicula is about 80//, in diameter in 

 mature proglottids and extends mediad and proximad for a distance 

 of about 850/*, coming to lie here near the anterior end of the proglottid. 

 It then curves usually to extend mediad and distad for a distance of 

 about 225/* where it ends in the slender vas deferens. The vasa effer- 

 entia are in a large part plainly visible. The vesicula seminalis if 

 closely examined is seen to be somewhat sinuous; but the effect is that 

 of a straight tube taking the course mentioned. At its extreme inner 

 end just at this juncture with the vas deferens it has glandular walls. 

 The testes are spherical and 65/* to 80/* m diameter. They are all 

 dorsal and extend from excretory duct to excretory duct in the distal 

 end of the proglottid. The number was found to be about 70 which 

 agrees with the account of Stiles. 



The vagina and vaginal pore are anterior to the cirrus pouch. For 

 about the first 185/* of its length the vagina is a very small, heavy- 

 walled tube which is perfectly distinct when once recognized. Beyond 

 this point it is very indistinct and usually can be traced only by the 

 vacuolated appearance of its course. In a few cases, however, it can 

 be seen very indistinctly anterior to the cirrus pouch, crossing the 



