Oll the structurc of Tnenia corifusa Ward. 479 



the börder of the va^iiiii (Kig. 7). The semiiial vcsiclc, as dcscribed 

 above, also lies inside of the sac. 



The genital porc. The genital pore (Fig. 4 p) nr generative 

 cloaca as it is sometimes called, is very ditierent in structure from 

 that of either T. saginata or solinrn (compare Figs. 7, 8). The pore 

 in the niajority of cases is distinct but not prominent and nieasures 

 in the sexually mature proglottids about 0.45 mm in diameter by only 

 0.05 to 0.08 mm deep. This extreme shallowness is almost sufficient 

 ground in itself to exclude this form from belonging to the above 

 named species ; for example, T. saginata, according to Leuckart 

 (1886, p. 440), has a wide pore or a funnel-like cavity, 0.22 mm deep 

 (Fig. 8 p). The pore in T. conßisa, contains a large plug-like pro- 

 jection (Fig. 4 pj)) at the outer extremity of which the seminal duct 

 opens. This plug is so large in fact that the cloaca is almost <>b- 

 litcrated (Fig. 7) beiug only a slight depression left between the edge 

 of the plug and the lip of the pore, due to the rounding off at the 

 end of the former. It generally extends out even with the edge of 

 the proglottid and sometimes a trifle beyond. As mentioued above, 

 tlie cirrus opens out about its center and when not protruded there 

 is a slight iuvagination or pit at the end of the plug. The cirrus 

 when thrust out, is wholly outside the cavity, judging from which, 

 one is inclined to think that copulation between the organs of the 

 same proglottids does not normally occur. The vagina, to be de- 

 scribed later, opens back of the plug, between it and the posterior 

 edge of the cloaca. 



The various muscles layers of the wall are little if any changed 

 in the region of the pore. No special sphincter muscles for the 

 whole pore is present. The slight pit which forms the cloaca, is 

 dii)ped into by the cuticula (Fig. 7 c. u) which then turns up the 

 side of the plug and finally down into the cirrus opening. Thus 

 the cirrus and Vas deferens are lined by a continuation of the 

 body wall. 



The pores are not regularly alternating on the proglottids but 

 in the main, in a given number, they about balance (Fig. 1). They 

 always lie back of the middle of the segment, this arrangement be- 

 coming niore pronouuced as the proglottids increase in length. They 

 iucrease but slightly in size with the increasing age of the proglottid 

 and in the long ripe Segments, in which the central plug has about 

 disappeared, they are more or less shrunken or collapsed internally, 

 still however, possessing a distinct outer lip or ring. 



