NEW ASEXUAL TAPEWOK.M. 849 



therefore there is no growth of the worm when it has arrived 

 at sexual maturity. This conchision, which fits the facts that I 

 am able to set forth, agrees also, it may be pointed out, with the 

 very worm-like cysticei'coid stage. There is, so to speak, not 

 much necessity for this immature worm to grow in length before 

 assu.ming the sexual condition. Far otherwise is it with the 

 typical Cysficerci, which are provided with but short strobila 

 as compared with the mature forms of their species. There is 

 at the very least a relation between the two series of facts which 

 is worth noting. It seems to me to be furthermore likely that 

 at no period are there sexual ducts developed — at any rate, no 

 female ducts. This latter circumstance, if true, is not new ; for 

 the absence of a female orifice has been asserted in more than 

 one genus of worms belonging to more than one family, 

 AjMrina among the Anoplocephalidse and many genera among 

 the Acoleidae are instances to the point. It is mainly, indeed, 

 the plain absence of a cirrus-sac which leads me to believe that 

 this worm possesses a dioecious habit so rare in this group. 



§ Gene^'ol Resume and SysteTnatic Fosition. 



It is, I think, obvious from the foregoing account of the 

 sexual form of this worm that it is the representative of a new 

 genus which differs in a good many particulars from any known 

 form. It will be convenient to give a short resume of the 

 essential characters of this worm, for which the name already 

 given to what I regard as the asexual form may be retained. 

 My reasons for retaining the name of the asexual form ai'e 

 firstly that I have been able to give a more complete account 

 of it than of the presumed sexual form of the same Cestode, 

 and secondly that I cannot fully define the sexual form, concerning 

 whose identity with the asexual form, moreover, some doiibt may 

 be considered to remain. 



In any case the following are the principal characters of the 

 sexual worm : — Length 86 mm., greatest breadth 6 mm. Head 

 with two rows of hooks 16 in each row, the hooks of the anterior 

 row twice the size of those of the second roAv. Suckers normal 

 and unarmed. No neck ; strobila consisting of numerous pro- 

 glottids very short and not appreciably longer at posterior end of 

 worm. 



Body flat, thicker anteriorly. Cortex about the same diameter 

 as medulla. Two layers of bundles of longitudinal muscular 

 fibres in cortex. "Water vascular tubes two on each side lying 

 side by side ; dorsal (?) tube with thick muscular walls. A trans- 

 verse vessel in each proglottid forking round dorsal vessel to join 

 ventral at two points. No water vascular network present. 

 Nervous system consisting of a larger lateral trunk and two 

 smaller trunks, one dorsal and one ventral, connected by many 

 cords in each proglottid to main trvmk. The sexes are apparently 

 separate or the worm is protogynous or protandrous throughout. 



