ON SOME AUSTRALIAN CLADOCERA. 481 
Rostrum long and recurved. Surface of the carapace 
pitted. Ocellus smaller than the eye; nearer it than to the 
tip of the rostrum. Antennules less than half the length 
of the rostrum. ‘Tail-piece strong, S-shaped behind the 
anal prominence, fifteen groups of anal spines, end-claws 
each with one large and one small denticle at the base. 
Length °45 mm. 
This form was collected from a pond at Sydney University 
in June. Type specimen in the Australian Museum, No. 
P 4334. 
CHYDORUS CLELANDI Sp. n. 
(Plate XLII, figs. 17, 18.) 
This isa very small form, the largest specimen examined 
only attaining 0°38 mm. Seen laterally, the carapace has 
a rounded form; the dorsal margin is strongly arched, join- 
ing the posterior edges at an obtuse angle; the ventral 
edges of the valves are also strongly arched; the posterior 
edges are very short and gently curved. | 
The head is produced into a long acute rostrum, closely 
appressed to the trunk; the dorsal margin forms an even 
curve with that of the carapace. 
The eye is large for such a small form; the ocellus is 
slightly smaller and situated nearer to the eye than to the 
tip of the rostrum. 
The antennules are short and rather thick, reaching 
about half the length of the rostrum. 
The surface of the carapace is pitted. The carapace is 
thickened along the ventral and posterior edges. ‘The 
ventral edges bear a row of short bristles. 
The tail-piece (fig. 18) is comparatively wide, with a very 
prominent supra-anal angle; twelve spines are present on 
the infra-anal margin. The end-claws are long, with 
Ee—Deccember 4, 1918. 
