ANATOMY OF THE CESTODA 



295 



convoluted or twisted, and frequently possesses a dilatation termed 

 the vesicula seminalis. It finally enters the cirrus pouch, which is 

 usually elongated ; within the cirrus pouch lies the protrusible cirrus, 

 which is not uncommonly provided with hooklets. 



The male sexual orifice almost always opens with that of the 

 vagina into a genital atrium, the raised border of which rises above 

 the edge of the segment and forms the genital papilla (fig. 191). 



The vagina, like the vas deferens, usually runs inwardly and 

 posteriorly, where it forms a spindle-shaped dilatation (receptaculum 

 seminis) ; its continuation, the spermatic duct, unites with the 



ut. 



FIG. 193. Diagram of genitalia of a Cestode. g.p., genital pore; $ ^, male 

 and female ducts opening into genital sinus; c.s., cirrus sac; v.d., coiled vas 

 deferens ("outer seminal vesicle "); vag. , vagina ; sem. rec., seminal receptacle ; 

 sp. d. t spermatic duct ; C.c. t fertilization canal ; vit. d. y vitelline duct ; sh. g. , shell 

 gland; ut. c., uterine canal; tit., uterus; Ov., ovary; /, pumping organ. 

 Cf. figs. 191 and 233. (Stephens.) 



oviduct, the common duct of the ovaries (fig. 191). The ovaries, 

 usually two in number, are compound tubular glands in the posterior 

 half of the proglottis, which extend into the medullary layer, but 

 ventral to the median plane. 



At the origin of the oviduct there is frequently a dilatation pro- 

 vided with circular muscles (suction apparatus), which receives the 

 ovarian cells and propels them forward. After the oviduct has 

 received the spermatic duct the canal proceeds as the fertilization 

 canal, and after a very short course receives the vitelline duct or 

 ducts, and then the numerous ducts of the shell glands (ootype). 

 [Although the nomenclature of these parts varies, we may consider 

 the oviduct as extending from the ovary to the shell gland and 

 as receiving the spermatic duct and then the vitelline duct and the 

 ducts of the shell gland. The short piece into which the shell gland 

 ducts open corresponds to the ootype in the flukes, but in the tape- 

 worms this portion of the canal is seldom dilated. From this point 



