6 ILLINOIS BIOLOGICAL MONOGRAPHS [356 



are somewhat longer. The scolex is compact, 700/u, long by 475/x broad, 

 the greatest width being near the anterior end. Posteriorly the scolex 

 tapers uniformly, until it merges into the neck, which is 290/x broad. 

 The suckers open nearly directly forwards. A circular groove about 

 the scolex at the level of the suckers makes it appear as if the tip of 

 the scolex were contracted somewhat within the rest. 



The genital pore is always on the right margin, about four-fifths 

 the length of the proglottid from its anterior end. It is relatively large 

 and deep as compared with the same organ in related cestodes. The 

 cirrus pouch is much larger than in other known members of the genus, 

 both in length and breadth, its median end lying well across the excre- 

 tory ducts. Its inner end is rounded and its lateral end only slightly 

 tapering. Across the middle its diameter is considerably less than at 

 either end so that its outline is somewhat like that of the figure 8. The 

 median end is occupied by the vesicula seminalis. The vas deferens is 

 not enlarged nor greatly coiled. An elongated prostate gland lying in 

 the anterior end of the proglottid empties into the vas deferens near 

 the cirrus pouch. The testes are dorsal, occupying the entire median 

 field to the left of and anterior to the vitelline gland and receptaculum 

 seminis, and partly underlying the latter. In the distal half of the 

 left side the testicular field extends laterad beyond the ventral excre- 

 tory duct. The testes number 30 to 40 and are mostly 70 to 80/x long, 

 the breadth being somewhat less. They break down early, but the 

 membranes remain intact and the individual testes are easily distin- 

 guishable. 



The vagina lies entirely posterior to the cirrus pouch, and in the 

 same dorsoventral plane. Its coils are thickly beset with glandular 

 cells. The receptaculum seminis is large and slightly longer anteropos- 

 teriorly than laterally. It lies directly in front of the vitelline gland, 

 and does not reach laterad to the ventral excretory duct as is the case 

 in other species of the genus. The ovary is a semicircular mass, reaching 

 nearly across the median field. In immature stages 12 to 15 lobes can 

 be distinguished which radiate in all horizontal directions; but before 

 the ovary matures these lobes become indistinguishable. The ovary is 

 not located nearer the pore side than the other, the mouth of the oviduct 

 being as often to the left as to the right of the median line. The 

 vitelline gland however is distinctly nearer the pore side. It is of the 

 shape most usually found in this group, being composed of a large 

 median and a smaller lateral portion connected by a transverse portion. 



The uterus, just before sexual maturity, is a network of tubes in 

 the anterior two-thirds of the proglottid. In the median field it extends 

 distad to below the upper limit of the ovary, ventrad of the latter. The 



