280 DR. F. E. BEDDARD ON 
difference, and adds to the possibility of generic difference. 
Indeed, v. Janicki admits the uncertainty of the inclusion of 
this species within the genus Oochoristica. No information is 
given of the ripe ova; but a small circular space lying 
in front of the ovary and marked in his fig. 5 with a ‘“‘?” is 
possibly to be regarded as the uterus. In any case, quite apart 
from the generic identity of ‘‘ Oochoristica” didelphydis, there 
can be no possible comparison between this species and 
Oochoristica marmose. The points of difference are too many 
and too important. 
In comparing Oochoristica marmose with other species of the 
genus, habitat comes first into consideration and then the 
systematic position of the host. There are only two species of 
Oochoristica from South American Marsupials known at the 
present time; and these are O. bivittata and O. didelphydis 
recently described by v. Janicki*. 0. bivittata is a much more 
slender worm than the one described here by myself ; the greatest 
diameter is only °9 mm. It agrees generally in the unarmed 
scolex, in the fact that the vagina opens behind the cirrus-sac, 
and in the imbedding of the ripe eggs singly in the parenchyma, 
and in smaller details, which are, nevertheless, of systematic 
importance. There is, in fact, no doubt as to the generic identity 
of the two worms. The differences, however, are quite of 
specific value. The complication of the excretory system 
of O. marmose contrasts with the simple transverse vessels of 
O. bivittata. It is to be noted, however, that in all three species 
from Didelphys (the genus Marmosa but slightly differs from 
Didelphys) there are only two main longitudinal trunks—a point 
of similarity which is of interest. The generative organs are 
quite unlike in the two species in a number of features. The 
position of the gonads contrasts, and the testes are very few in 
number, in O. bivittata. This may, however, be partly due to the 
maturity of the segments, in one of which they are figured as not 
exceeding five in number clustered together behind the vitelline 
glands. Finally, the ripe eggs, though scattered singly as in 
other species of Oochoristica, are limited to, the sides of the 
proglottids in O. bivittata. 
I conclude with a definition of the new species, which is as 
follows :— 
Oochoristica marmose, sp. n. 
Length at least 54 mm.; diameter 2°38 mm. Scolex unarmed, 
with suckers directed forwards, genital pores anteriorly situated 
in proglottid, alternate. Cortex not so wide as medulla. Longi- 
tudinal muscles forming a layer of bundles consisting of 10 
or more fibres, above which are scattered fibres. Water-vascular 
system consisting of two longitudinal vessels on each side connected 
by a rich plexus of rather large branches. Testes very numerous, 
* “Studien an Satigethiercestoden,’ Zeitschr. wiss. Zool. Ixxxi. 1906, p. 505 ; 
and a preliminary account in Zool. Anz. xxvii. 1904, p. 770. 
