REPTILIAN TAPEWORMS. 247 



hiiufig ein den Sclieitel des Scolex einnehmender, kleiner flinfter 

 Saugnapf entwickelt ist. Das Vorhandensein eines scheitel- 

 stfindigen Saugnapfes ist wohl ein urspriingliches, den niederen 

 Formen der Tanien eigenes Yerhalten." The balance of opinion, 

 therefore, seems in favour of regarding an apical organ as charac- 

 teristic of the Ichthyotteniidse, but to leave it for the present 

 doubtful whether we are to describe this organ as a sucker or as 

 a rudimentary rostellum. It appears to me tha,t there is evidence 

 in favour of believing that both structures are present among 

 the members of the family Ichthyotseniidee, and that Acanthotcenia 

 is to be characterised by the possession of a rostellum while 

 Solenotcenia has an apical sucker. But it may be that both 

 structures have a common origin. 



In transverse sections of the neck region muscular fibres, 

 forming a longitudinal layer, are visible. But these fibres do 

 not form a compact layer ; they are scattered singly through the 

 parenchyma, and not massed into bundles, as in Acanthotcenia, 

 or into a definite layei-, as in some other Ichthyotseniids. Further 

 back the fibres of the longitudinal layer are arranged in bundles ; 

 these bundles are small, consisting of but few fibres and with 

 considerable interspaces, where there are no longitudinal fibres 

 delimiting the cortical from the medullary layer. The position 

 of the bundles, and therefore the length of the interspaces, are not 

 regular, and the fibres of each bundle (in which I have counted 

 about 4-7) ai-e apt to be placed one on top of the other, thus 

 forming a line at right angles to the long axis of the transverse 

 section. Longitudinal sections through the proglottids illustrate 

 also the scattered condition of the small bundles of longitudinal 

 fibres ; for there are to be seen frequent gaps where the coi-tical 

 layer is not separated from the medullary layer by these fibres. 

 There are apparently, as will be seen in text-fig, 47, transverse 

 muscular fibres in the medullary layer. 



The generative system of Solenotcenia is like that of other 

 Ichthyotseniids, with certain peculiarities of its own and features 

 that it shares only with Ophidotmnia. The accompanying text- 

 figure (text-fig. 48) is a view of a mature proglottid mounted 

 entire, and it shows the general arrangement of the various 

 parts of the generative system. The marginal generative pores 

 lie quite at the middle point of the segment, and the cirrus is 

 seen to be occasionally protruded. As in other Ichthyotseniids, 

 the male pore is sometimes in front of and sometimes behind the 

 vaginal pore. 



The vitelline glands are very plain in such preparations, and 

 form the usual strips extending through the grea.ter part of the 

 length of the proglottid. Marotel * has represented the vitelline 

 glands of Jchthyotoinia calmettei as consisting of numerous and 

 separate follicles. I find in the present species in certain regions 

 an obvious separation between the adjacent follicles ; elsewhere, 



* Arch, de Pavasitol. 1899. p. 34. 



