ON REPTILIAN TAPEWORMS. 243 



PAPERS. 



20. Contributions to the Anatomy and Systematic Arrange- 

 ment oi: the Cestoidea. By Fkank E. Beddarp, M.A., 

 D.Sc, F.R.S., F.Z.S., Prosector to the Society. 



[Received January 14, 1913 ; Read March 4, 1913.] 



IX. On a New Genus of Ichthyot^niids. 



(Text-figures 45-53.) 



Index. 



Page 



Account of Solenotcen'm viper is, gen. at sp. n 243-261 



Resume and General Conclusions 261 



A considerable number of examples of a rather large species of 

 tapeworms clearly referable to the family Ichthyotseniidse was 

 obtained in 1911 from the Crossed Viper (Zac^^sts alternans). It 

 is only recently that I have subjected these specimens to a careful 

 examination, and they prove to represent a species which is most 

 nearly akin to my recently constituted genus Ophidotcenia *, but 

 present characters which seem to me to justify their inclusion 

 within a new genus, which I term, by reason of a salient external 

 character of the ripe proglottids, Solenotcenia. This character is 

 obvious in fvilly mature proglottids (see text-fig. 49, p. 250) as 

 a well-marked ventral groove extending along nearly the whole 

 of the proglottid on the ventral surface. It is generally quite 

 visible to the naked eye, when it appears to vaiy in length in 

 difierent proglottids, being in fact a mark of maturity. 



The general aspect of this tapeworm is that of other Ichthyo- 

 ta3niids, and it is quite like Ichthyotcenia gabonica, which I have 

 recently described, so far as external characters go, with the 

 exception, of course, of the ventral groove, to which I have just 

 referred. The length is at least 5 or 6 inches, and the breadth 

 of the ripe proglottids i-ather more than 2 mm. The body does 

 not narrow much at the head end, and the scolex is more than 

 1 mm. wide. There is a neck which is at first narrower than 

 the scolex. In transverse sections the scolex showed no pecu- 

 liarities that I could detect. There was hardly any rostellar 

 region, the suckers being very large. 



In addition to the four large suckers (which are of course 

 unarmed, like those of other Ichthyotseniids), there is a very 

 small apical structure of a somewhat different nature. It is less 

 cup-shaped and more funnel-shaped than the lateral suckers, 

 narrowing rapidly at its internal end. At the same time the 



* See P. Z. S. 1913, p. 25. 



