412 
Cestode Genus Oochoristica 
earliest rudiment is a flattened sac with thin cellular walls, lying just ventrally 
to and in front of the ovary. It rapidly sends out egg-containing processes, at 
first in front and at the sides of the ovary, and eventually all over the segment, 
as far as the limits of the medulla. This stage is reached within about six 
segments, and the ova then become scattered throughout the parenchyme. 
The history of the uterus and egg-cavities, in fact, appears to be almost pre¬ 
cisely as in the species already described, the chief difference being the more 
forward position occupied by the uterus. The ova go through the same stages 
in the formation of their envelopes, and have a precisely similar appearance. 
When fully developed, the outer membrane measures about 60 fi in diameter, 
and the onchosphere itself 37 p. 
It may be useful now to give a simple key for the separation of the three 
forms from lizards to which special attention has been given in this paper. 
They may be simply distinguished as follows: 
A. Maximum width of strobila over 2 mm. 
Testes more than 60 in number ... ... ... ... ... O. zonuri. 
B. Maximum width of strobila less than 2 mm. 
Testes less than 60 in number 
B 1. Width of scolex less than 0*4 mm. 
Transverse excretory vessels simple ... ... ... 0. truncata. 
B 2. Width of scolex more than 0-4 mm 
Transverse excretory vessels form an elaborate network O. agamae. 
OOCHORISTICA and LINSTOWIA. 
As Beddard (1914 and 1916) has pointed out, there seems to be very little 
ground for the separation of these two genera, and certainly no justification 
for placing them in separate families. In endeavouring to find some difference 
of generic value, this author says (1914): “ One structural feature occurs to me 
as being of possible use in better defining the two genera.. . . 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.” He then goes on to explain that the kind 
of difference meant is that shown by the two forms that he has just been 
describing —Linstowia ameivae and Oochoristica marmosae. 
The points of difference mentioned by Beddard, as regards the uterus and 
egg-capsules, may be briefly summarised as follows (supplemented in one 
particular from Beddard’s observations (1913) on another species of Oocho¬ 
ristica, from the Tamandua Anteater). 
Oochoristica (marmosae). 
Uterus at first a well-marked posterior trans¬ 
verse tube, with lateral diverticula. 
These have well-marked walls, though no 
special lining. 
Linstowia (ameivae). 
Uterine cavities from the first less strongly 
marked off, and do not form a coherent 
group. 
Walls of cavities not definite. 
