On some West-Australian Entomostraca. 2 
The tail, which, as usual, does not admit of being wholly 
withdrawn between the valves, but is constantly seen pro- 
jecting behind them, exhibits the structure characteristic of 
the genus. At about the middle, the posterior, or dorsal 
edge forms a conspicuous bulging, and at this place the 
anal orifice occurs. The outer part of the tail, beyond the 
anal orifice (see fig 4), is conically tapered, and carries on 
each side a series of about 8 denticles, the outermost of 
which is placed at some distance from the others and 
terminates in 2 unequal points. The remaining 7 denticles 
are very delicate, somewhat flattened, and finely ciliated on 
both edges. The caudal claws are of moderate length and 
perfectly smooth, without a trace of secondary denticles. 
The caudal setæ somewhat exceed the tail in length, and 
are distinctly biarticulate and densely ciliated. 
The ephippium, seen laterally (fig. 5), is of an oval 
triangular form, being broadly rounded in front, and coni- 
eally produced behind, It is very coarsely sculptured in 
the centre with raised knob-like prominences, and always 
contains but a single egg-ampulla placed longitudinally. 
The adult male (fig. 6) is scarcely more than half 
as large as the female, and on the whole resembles the 
males of the 3 other Australian species, though it may be at 
once distinguished from them by the peculiar bend of the 
ventral edges of the valves, which exactly agrees with that 
found in the female. The head is comparatively much 
larger than in the female, and appears obtusely truncated 
in front, forming between the bases of the antennule a well- 
marked obtuse prominence. 
The antennulæ, as in the males of the other species, 
are very powerfully developed, fully equalling half the length 
of the body. Their basal part is somewhat thickened, and 
