230 T. B. ROSSETER ON HYMENOLEPIS FRAGILIS. 



specimens I have not a perfect worm, that is to say, I have not 

 one that possesses a scolex with the rostellum and eight hooks, 

 and only two specimens whose terminal proglottides have de- 

 veloped into uterine segments bearing the hexacanth or six- 

 hooked brood. Yet the strobila, taken as a whole, is so unlike 

 that of T. fasciata, T. gracilis, or T. octacantha with eight hooks, 

 or T. sinuosa with its spinous bulb, and the male generative 

 organs of the above-mentioned species are so dissimilar from my 

 specimens that, in spite of its being minus the hooks, I have no 

 hesitation in determining my species of tape-worm as Krabbe's 

 Taenia fragilis. The largest specimen I possess measures seven 

 millimetres less than Krabbe's ; but then mine are minus the 

 scolex and neck. The evolution of the strobila and the varied 

 formation of the segments is shown in Fig. 1, Sees. 1-10. 



The male genital pore (Fig. 1, Sec. 10, M.G.P.) is a simple 

 circular opening in the dorso-anterior portion of the segment 

 on the lateral margin of the same. There are three testes 

 (Sec. 10, Fig. 2), one situated proximally on the posterior margin 

 of the segment, and the other two distally in the vertical plane, 

 the one being superimposed upon the other ; the efferent ducts 

 of the latter form a junction immediately on leaving the gland. 

 The efferent duct of the proximal testis runs distally, meets and 

 makes a junction with the ducts of the distal testes, and thus 

 forms the vas-deferens (Fig. 2). It still continues its course 

 distally for a short distance, then sharply curves, or swings 

 round, and enters the bursa, where it becomes the vas-deferens 

 interior. The testes have a diameter of 0*062 mm. 



That portion of the male genitalia which in the majority of 

 other known species of tape-worm whose organs of reproduction 

 have been studied has received the name of cirrus-pouch, is, in 

 this instance, a composite sac, and is situated in the dorso- 

 anterior-dextral portion of the segment. This sac comprises 

 the prostate gland, the vas-deferens interior, the vesicula-semi- 

 nalis, with its coiled vasa-efferentia, and the cirrus, with its 

 sheath and pouch. Thus, as I have said above, it is a composite 

 sac containing, with the exception of the testes, the whole of 

 the male organs of generation, and I purpose denominating it 

 in this instance the " bursa genitalium." It is - 445-0*455 mm. 

 long, and through the median axis 0"097 mm. in diameter 

 (Fig. 3). 



