206 On a new Tentaculate Cestode. 
opens the water 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 Rhabdometra 
cylindrica that no description is necessary ; aud this applies 
to the water vascular system. On the other hand, I have 
detected certain minutiz in which the generative system 
differs, and I give the facts for what they may be worth as 
marks of differentiation. The testes are posterior in position 
and are developed dorsally, laterally, and ventrally, as in 
Rh. 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. cylindrica 
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 in 
R. cylindrica. 
Both 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 Rh. cylindrica*. This 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 present 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 in 
the younger paruterine bodies of RA. cylindricat. 
It seems therefore to be clear, that the Cestode which 
forms the subject of these remarks would be undoubtedly 
referred to the genus Rhabdomeira, were there no knowledge 
* See text-fig. 5, p. 868, of my memoir just cited. 
+ I take this opportunity of adding a new fact of some little interest 
to what is known of the anatomy of Rhabdometra cylindrica. I found 
in the case of one proglottid only, out of a number which 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 middle of the ventral 
surface. It will be observed that the occasional existence in the present 
species of a separate uterine pore is more striking as a retention of an 
archaic state of affairs than in Dasyuwrotenia, where (see Beddard, 
P.Z.S. 1915, 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 Lhabdometra a comparison is undoubtedly to be made with the 
Pseudophyllidea and the Ichthyotzeniids, and not with the dorsal and 
ventral pores, connected though they are with the egg-holding system, 
of Amabilia and (?) 3 Schistotenia. 
