TWO NEW TAPEWORMS. 701 



If my figure (text- tig. 1. p. 702) be compared with Fuhrmaun's *, 

 illustrating Cotugnia polyacantha^ it will be seen that in the 

 latter species the conditions are the exact reverse of that just 

 described. In Coivgnia polyacantha the area of the rostellum is 

 much greater than that of any one of the suckers, which are thus 

 small by comparison. The second point to which I draw atten- 

 tion is the apparent occasional absence of hooks. As I have seen 

 these structures, it is fair to suppose that where they were not 

 seen they did not exist. This is a very important matter in the 

 discrimination of Cestodes ; it is obviously not yet certain that 

 all bookless. genera are really so, except throug'h loss of hooks in 

 individuals. 



In transverse and longitudinal sections the rostellum is seen to 

 be a relixtivel}' veiy small structure, which entirely bears out the 

 appearances to be noted when the scolex is seen as a whole, either 

 fresh or, after preservation in. alcohol, in glycerine. The re- 

 tracted rostellum is shown in text-fig. 1, where it is seen to be 

 a very sucker-like structure, although, as already stated, it is 

 very much smaller than the actual suckers. 



It is a cup-shaped organ, along the edges of which the hooks 

 can be seen to be implanted. The rostellum, in fact, is very 

 small and simple. Its substance chiefly shows muscular fibres 

 running across its short diametei", i. e. in the longitudinal axis of 

 the body of the worm. Outside of this is a layer of much less 

 diameter, which suggests a subcuticular layer. The simplicity 

 and small size of the rostellum is so far like that of Tcenia 

 sagiiiata, as figured and described by Leuckart f. It is, perhaps, 

 more to the ipoint to compai'e the rostellum of the present species 

 with that of more nearly related foi'ms. 



Within the genus Cotugnia itself the I'ostellum appears to be 

 usually large. In structure that of C. collini is said by Fuhrmann 

 to resemble that of a species of Darahiea. There are, however-, 

 in Davainea, as Fuhrmann himself has pointed outi, consideiuble 

 differences among the species. There is, however, a remarkable 

 likeness between the present species of CoUignkt and Ophryo- 

 cotyle insignis, which may well be of significance. This latter 

 Cestode has, in the first place, a lens-shaped rostellum proper, 

 which, as Liihe has pointed oiit §, is at least often characteristic 

 of Davainea. That is much the same form as I figure here in 

 Cotugnia 'tnargarekt., where, however, it is more cup-shaped a-nd 

 thus sucker-like. 



Liihe, however, speaks of the rostellum of Davainea ^truthimiis 

 as having a very short antero-postei'ior diameter and as being 

 concave anteriorly, thus approximating in shape to a sucker. 

 I did not, however, find this to be the case with a species of 

 Davainea from StriUhiv masaicns, which is very probably identical 



* Centralbl. f. Balct. n. Paras, xlix. 1909. p. ]2l, fig. 38. 



t 'The Parasites of Man ' (Engl, trans, hy Hoyle), FA]nh. 1886, p. 435, fig. 247. 

 I Cf. e.g. in Centralbl. F.akt. u. Paras. \Vix. fig. 10, p. 101 & fig. 24, p. 113. 

 § Zool. Anz. Bd. xvii. 1894, p. 280. 



