206 On a new Tentaculate Cestode. 



opens the \v;iter vascular system by a pore. I mention this 

 for the reason that the characteristics about to be referred to 

 may not be those of the fully mature species. The cortex 

 and muscular system are so like those of R/tabdometra 

 cyiindi'ica that no de3cri[)tion is necessary; and this applies 

 to tiie water vascular system. On the other hand, I liave 

 detected certain minutiie in which the generative system 

 differs, and I give the facts for what tliey may be worth as 

 marks of differentiation. The testes are posterior in position 

 and are developed dorsally, laterally, and ventrally, as in 

 RIt. cylindrica. The cirrus-sac seems to be rather longer 

 than in the last-named species ; it extends well over the 

 ventral vessel of the water vascular system — in Rh. cyl'indrica 

 the cirrus-sac only reaches as far as, or just over, the 

 same water vessel. The receptaculum seminis of the new 

 species is more elongated in form than is that organ iu 

 R. cyUndrica. 



Jioth the uterus and the paruterine organ of my new 

 tentaculate species correspond very closely in relative size 

 and shape to the same organs in the less fully mature 

 proglottids of Rk. cyl'indrica* . Tiiis is also the case with the 

 terminal segment of the worm. I find, however, that the 

 end of the paruterine organ in the new species, where it 

 comes into contact with the uterus, has no heap of calcareous 

 bodies such as are jjresent in the species with which I am 

 comparing it ; this seems to be a real difference, though the 

 heaps of calcareous bodies are at least not always present iu 

 the younger paruterine bodies of Rh. cylindrical. 



It seems therefore to be clear that the Cestode which 

 forms the subject of these remarks would be undoubtedly 

 referred to the genus Rluibdumetra, were there no knowledge 



♦ See text-fig. 5, p. 8(iS, of mv memoir just cited. 



t I tiike this opportunity of addiiijj: a uew fact of some little interest 

 to wlial is known of tlie anatuniy of Tihuhdumetra ci/Iiiidricii. 1 found 

 in llie case of one ])ioglottiil only, out of a number wiiicli I examined, a 

 duct leading from the anterior region of the uterus, which was followed 

 to its opening on the ventral surface of the segment by an involution of 

 the subcuticular layer as near as possible in the jniddle of tlie ventral 

 surface. It will be observed that the occasional existence in the present 

 species of a separate uterine pore is more striking as a reteiuion of an 

 archaic «tate of aftairs than in Dasyurotcenia, where (see Beddard, 

 1'. Z. S. lOlo, p. 190, text-fig. 8) the occasional uterine pore is lateral 

 and involves the lateral water vascular tube. It is clear that in the 

 genus I\liiil)(I<»)irtr(i a comparison is iindoubti-dly to be made with the 

 I'seudophyllidea and the Jchtliyoticuiids, and not with the dorsal and 

 ventral jxires, connected though they are with the egg-holding system, 

 oi Amabiiiii and (!■') Sc/iistoi<cni(i. 



