698 



THE ANATOMY OF BOTHEIOCEPHALUS LATUS. 



the dorsal surface of the uterus, the loops of which it accompanies 

 in more or less close apposition (Fig. 365), but on the whole the 

 bendings which it exhibits are smaller and less ample. There is an 

 obvious difference here between the present species and the Teenies, 

 and this is further emphasised by the fact that the vas deferens in 



this worm is not only considerably 

 wider, but also bears a sheath of 

 circular muscle fibrils, which, like 

 the bulbar swelling at the upper 

 end, serve to force forward the en- 

 closed spermatozoa. According as 

 the number of the latter is large or 

 small, the width of the canal varies, 

 increasing sometimes from 0'035 

 mm. to double that and more, be- 

 sides exhibiting, at certain places, 

 considerable varicose swellings. 

 This is seen most strikingly and 

 most frequently at the lower end, 

 which, being filled with semen, not 

 unfrequently forms a conspicuous 

 " seminal cistern " (Landois and 

 Sommer), shining through the first 

 front of the ovary, in the form 

 body, sometimes measuring 0'2 

 mass is brought into this re- 



-/*'^^& 



Fig. 365. — Male generative organs of 

 Sothriocephalus latus, seen from the dor- 

 sal surface ; c.p., cirrhus-pouch ; s., swell- 

 ing adjacent to it ; ud., vas deferens ; s.c, 

 seminal cistern; t,, testes; ut., uterus; 

 s.g., shell-gland ; ov,, ovary, (x 20.) 



coils of the uterus, just in 

 of a darkish, saccular, irregular 

 mm. in thickness. The sperm 

 ceptacle by the afferent canals, which in a variable, but always 

 limited, number lead into -the " cistern " from right and left, and 

 connect it through their much ramified lateral branches with/ 

 the testicular vesicles. The irregularity in the number of afferent 

 ducts is due for the most part to a very early bifurcation. I have 

 seen joints in which the lower end of the vas deferens divided into 

 two limbs, which extended almost at right angles into the lateral 

 areas, there to ramify further, and also others in which, on either 

 side, three or four collecting ducts led into the " cistern." The branches 

 of the collecting ducts, or the ducts themselves when several occur, 

 are directed both backwards and forwards. Nor are they by any 

 means confined, to the area of the joint to which they really belong, 

 but extend beyond the boundaries, coming into connection with the 

 superior testicular vesicles of the following joint. 



contrary refers to a second small vesicle within the cirrhus-ponoh (Zoo. cit. , p. 50), and can- 

 not apply to the appended bulb. The latter was first discovered, described, and explained 

 by myself. 



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