256 ILLINOIS BIOLOGICAL MONOGRAPHS [256 



eral species of Ophiotaenia shows that if the vagina is in an anterior 

 position it extends farther anteriad before bending toward the genital 

 pore than it does when it occupies the posterior position. If these 

 vaginae are displaced by pressure then they ought to show evidence of 

 such displacement by their form or structure. This they do not do, as 

 an examination of the drawings (Figs. 111-115) will show. It will be 

 noted that when the vagina is anterior to the cirrus-pouch it usually 

 crosses the coils of vas deferens. In C. gerrardii the vagina, when 

 anterior, never crosses the cirrus-pouch. 



The testes lie in two broad fields which tend to coalesce in the 

 anterior region of the proglottid. Testes number about 240 in the 

 specimens from the Bureau of Animal Industry. Monticelli (1899) 

 found about 200 or more in each proglottid. Smith (1908) figures but 

 87 testes. There must be an enormous variation in the number of testes 

 or else Smith overlooked some of them, for in a preparation of an 

 immature proglottid from one of his specimens the writer counted 

 nearly 400 testes. In this proglottid, delineated (Fig. 113), the testes 

 are very small. In maturity many of them might be crowded down to 

 a lower plane and so might be overlooked. However, in his prepara- 

 tions the writer has not found evidence for this crowding. There is no 

 evidence that any of the testicular anlagen fuse together or degenerate. 

 As a rule the testes in this species measure 0.030-0.050 mm. in diameter 

 but in a specimen from lot 10.179 the testes measured as much as 0.080 

 mm. Monticelli (1899) says that they are about twice the size of the 

 vitelline follicles. The vas deferens (Fig. 112) in ripe proglottids is 

 thrown into numerous, heavy, spermatozoa-laden coils which extend in 

 a mass nearly to the middle of the proglottid. Within the cirrus-pouch 

 the ductus ejaculatorius makes a few coils before passing over into the 

 cirrus. The latter when protruded (Fig. 114), is short, thick and very 

 muscular. Monticelli 's description agrees with this statement. The 

 cirrus-pouch is short, broad and heavily muscled. Its length is about 

 0.23-0.25 mm. and its breadth about 0.10-0.15 mm. In maturing pro- 

 glottids the ratio of its length to the segment breadth is 1:5 or 1:6 

 while in ripe proglottids it is about 1 :4. 



These organs (Figs. 112-115) are arranged as in the Ophio- 

 taenia. The lumen of the vagina (Figs. 114, 190) near its opening to 

 the exterior is large. The vagina is here surrounded by a strong sphinc- 

 ter vaginae. There are no coils of vagina anterior to the ovary. A 

 receptaculum seminis has not been seen. Monticelli (1899) states that 

 it is present. The ovary is bilobed and it is situated in the posterior 

 part of the proglottid. The lobes are thick, broad and short. Their 

 outlines are more or less irregular. An oocapt, ootype, shell-gland, ovi- 



