ON SOME AUSTRALIAN CLADOCERA. 479 
The antennules, which are tipped with a bunch of sensory 
papillae, extend about half the length of the rostrum. 
The antenne have the structure characteristic of the 
genus; they are comparatively short. 
The tail-piece (fig. 14) is moderately strong and of uniform 
breadth throughout. The supra-anal angle which is distinct, 
is an obtuse angle. The end-claws are situated on a little 
prominence; they are rather strong and slightly curved; 
each has a rather large denticle removed a little from the 
base; there is also a very small secondary denticle at the 
base. The spines on the infra-anal margin are fairly short; 
there are about eleven pairs present; seven comb-like 
groups of bristles occur on either side of the anal furrow. 
This species in many ways resembles the larger form 
Pleuroxus inermis, described by G. O. Sars in “‘Freshwater 
Entomostraca from the neighbourhood of Sydney.” It 
differs however in the presence of a denticle on the postero- 
ventral corner and in the very different sculpturing of the 
carapace. 
Specific Characters.—Carapace seen laterally oblong oval 
in shape; narrowly truncated posteriorly; dorsal margin 
arched; ventral edges curved, protuberant in front; postero- 
ventral corner witha blunt denticle. Head small, termin- 
ating in a long slender rostrum. Sculpture of valves con- 
sists of a reticulation together with pits. 
Hye of moderate size, ocellus smaller, much closer to the 
-eye than to the end of the rostrum, Tail-piece of uniform 
breadth; spines on the infra-anal margin fairly small, seven 
lateral combs; terminal claws with two secondary denticles 
each, one large one small. Length 0°31 mm. 
Locality.—Collected at Port Stephens in August. Type 
specimen in the Australian Museum, No. P 4333. 
