TWO NEW SPECIES OF CESTODES. 283 
Australian forms limited to that country and to the two groups 
Marsupials and Monotremes. Here geographical range and 
the systematic position of the host concur with unusually large 
cirrus-sac as an anatomical character. But one of the two 
species, viz. Linstowia semoni, has a distinctly larger cirrus-sac 
than LZ. echidne ; and in my species LZ. ameive the cirrus- 
sac is not much smaller than that of LZ. echidne. One structural 
feature occurs to me as being of possible use in better defining 
the two genera Linstowia and Oochorisiica. But it is so little 
known that it cannot be used for the present and may after all 
turn out to be worthless. This concerns the imbedding of the 
ova in the parenchyma after the disappearance of the uterus. 
I have pointed out *, in describing the ripe eggs of a species of 
Oochoristica, that they are encircled by a cellular layer suggestive 
of a commencing paruterine organ like that of Davainea, etc. 
If it be found that this character also signalizes other South 
American species from Hdentates a separation might well be 
made. Furthermore, it is quite possible that the condition of 
the uterus may serve as a dividing-line, as it certainly appears to 
do in the case of two other mutually related genera, viz. 
Inermicapsifer and Zschokkeellat. The kind of difference that 
is meant by this suggestion is that shown by the two species 
described in the present paper, and has been put forward in 
detail above, accompanied by illustrations (text-figs. 2 & 5). 
In the meantime, it does not seem possible to form a reasonable 
definition of the two genera, and [ am strongly of opinion that 
there are no grounds at all for placing Oochoristica and Linstowia 
in separate families. 
* In a paper upon a new genus Wugonodeum in P.Z.8. 1913, p. 875, text-fig. 149. 
+ See P. Z.S. 1912, p. 607. 
os 
