On some West-Australian Entomostraca. 19 
Remarks.—This new species may be easily distin- 
guished from any of the other known Moinæ by the peculiar, 
flexuous bend of the ventral edges of the valves, as also 
by the form of the head in the female. 
Description of the female. 
The average length of fully adult, ovigerous specimens 
is from 0.7 mm. to 0.8 mm. The largest specimen found in 
my aquaria measured 0.9 mm., and it is therefore most 
probable, that this form never exceeds a length of 1 mm. 
It is accordingly by far the smallest of the 4 as yet known 
Australian species. 
The general form of the body (see figs. 1 & 2) agrees 
on the whole with that of the other species of the genus, 
being rather short and stout, with the head and carapace 
very sharply marked off from each other. 
The shell or carapace, which is defined dorsally from 
the head by a deep depression, has the dorsal part often 
enormously expanded, in order to make room for the numerous 
developing young ones. When these are ready to escape 
from the matrix, that part is sometimes found to project as 
a large, almost globular pouch sharply defined from the true 
valvular part, which in all specimens preserves its form quite 
unaltered. At the junction between the two, the carapace pro- 
jects posteriorly to a short obtuse prominence, immediately 
below which there is a slight notch in the hind edges. The 
ventral edges of the valves, which in all other known spe- 
cies appear almost straight and horizontal, are in the present 
form rather irregularly flexuous, projecting in the middle to 
an obtuse prominence, behind which the edges appear 
slightly concave, before joining the posterior margin. In 
