660 ON SOME MAMMALIAN TAPEWORMS. 



uterus. There was nothing like the formation of diverticula of 

 the latter walled by the condensed parenchyma. 



The characters of this worm may be briefly summed up as 

 follows : — 



Scolex lonarmed, ivith no rosfellum, only a raised area. Strohila 

 cominencing without an intermediate neck. Proglottides much 

 wider than long, except at the very end of the body. Proglottides 

 very 7iumerous, the length of worm being some 6 inches with a 

 greatest diaoneter of 6 mm. Genital pores unilateral. Excretory 

 tubes four, parallel to each other. Cortical layer of body as thick 

 as medjxdlary. Testes chiefly massed upon the side of the body 

 furthest from the genital pore, very numerous, median in position. 

 In addition, a small number of similar testes on either side of the 

 outermost excretory vessel of the pore side of the proglottid. Vas 

 deferens with a large coil and a vesicula seminalis above ovary ; 

 cirrus sac not lo7ig. Genital cloaca small, loith circular muscles. 

 Ovaries doiMe, on either side of innermost of excretory tubes of pore 

 side of segment. Yolk-gland on one side of same excreto7'y vessel 

 behind ovary. Shell-gland nearer to the middle of the body above 

 the yolk-gland. Seminal recejitacle, long and not m.uch swollen, 

 begins soon after the terminal chamber of the vagina. Uterus broad 

 and sac-like, occupying a great deal of the tniddle of the proglottid. 

 Many parihterine organs present in later stages. 



The characters given in the above paragraph are not distinctive 

 of any known genus of Tetracotylea. And I am, indeed, disposed 

 to think that ultimately it will be necessary to form a separate 

 genus for this worm from the Gambian Pouched Rat. In the 

 meantime, however, I do not burden zoological nomenclature with 

 an additional name until the possibility of its distinctness becomes 

 more settled. Besides it is also possible that the existence of this 

 species removes a barrier between the two genera Thysanosoma 

 and Anoplocephala. Until I had become aware of the numerous 

 paruterine organs, I was disposed to refer the worm to Anojdo- 

 cephala, with which genus it obviously has many points in 

 common. But the existence of these characteristic paruterine 

 organs — and in such great numbers — is a reason for removing it 

 from Anoplocephala and uniting it with Thysanosoma. On the 

 other hand, the latter geniis has either double or single sets of 

 generative organs, and, correspondingly, either two pores upon each 

 proglottid or alternating pores, while the Tetracotylean described 

 in the foregoing pages has generative pores all upon one side. 

 Nevertheless, the double set of testes seems to be a last trace of an 

 originally completely double set of gonads and ducts, such as occurs 

 in some proglottides of other Thysanosomas. If the small set of 

 the testes existing in this species upon the pore side of the ovaries 

 were to disappear it would be, as I think, impossible to separate 

 this genus from Anoplocephala or Zschokkeella ; but the definition 

 of those genera would have to be enlarged in order to take in the 

 numerous paruterine organs, which is, after all, perhaps the chief 

 reason for referring this worm to the subfamily Thysanosominse 

 which is mainly thus characterised. 



