TWO NEW SPECIES OF CESTODES. 279 
Kapsel beherbergt in der Regel ein einziges Hi.” ‘The structure 
figured by Zschokke *, and to which he refers in the above quota- 
tion, seems to be of the nature of a membrane and to be therefore 
quite like the membrane to which I here refer in Oochoristica 
marmose. It does not suggest a cellular layer such as I have 
figured in Oochoristica sp. As to the number of shells, whether 
thrown off by the embryo or not, which surround the embryo 
in the genus Oochoristica, there appear to be differences among 
different species. Cohn distinctly represents three shells £ in 
O. surinamensis, while Marotel § asserts the presence of only 
two in the Oochoristica of the European Badger, O. incisa of 
Raillet ||. 
§ Affinities of the Species. 
I have described this species as an Oochoristica; into the 
question of the definition of this genus I propose to enter later. 
In the meantime, it is necessary to enquire whether---apart 
altogether from the question of genus—it may not be specifically 
identical with Linstowia brasiliensis ™ from Didelphys tristriata. 
There is, I think, no possibility of confusing the two species, in 
spite of many points of general resemblance. In the first place, 
the simplicity of the water-vascular system of Dr. v. Janicki’s 
Species distinguishes it from mine. Furthermore, the fact that 
in Linstowia brasiliensis the ripe eggs of the posterior segments 
are limite 1 to the lateral areas of the segments militates against 
the identity of the two species now under consideration. ‘These 
differences appear to me to be suflicient, without going into a 
more detailed comparison between Linstowia brasiliensis and 
Oochoristica marmose. The same remarks apply to L. theringi**. 
Oochoristica didelphydis is too small a species (it measures only 
15 mm. in length) to be confused with the present one. Further- 
more, the scolex was absent, which increases the difficulties of 
identification. But it agrees with my species in having only 
two lateral vessels, of which the dorsal has a very fine lumen. On 
the other hand, the transverse tube is quite simple, which is not 
the case with that of O. marmose. The obliquely directed 
cirrus-sac of O. didelphydis contrasts with the perfectly straight 
one of O. marmose. The fact that in the former species 
the vagina opens on to the exterior in front of the cirrus-sac 
appears to me to be such an important difference, not only 
from my species, but also from the species of the genus 
Oochoristica, that it leads me to doubt the generic identity of these 
forms. And I would again point out that while the vagina 
of O. marmose is perfectly straight, that of O. didelphydis 
is much coiled. This appears to me to be quite a salient 
* Loe. cit. pl. xxiv. fig. 7. + P.Z.S. 1913, p. 875, text-fig. 149. 
t Arch. f. Naturg. 1903, p. 65, fig. 9. § C.R. Soc. Biol. 1899, p. 21. 
|| Loe. cit. t. cit. p. 23. 
| v. Janicki, Zeitschr. wiss. Zool. 1xxxi. p. 507. 
** ZLschokke, C.Bl. Parasit. xxxvi. 1904, p. 51. 
