ON SOME AUSTRALIAN CLADOCERA. AD 
The surface of the carapace is marked by numerous small 
pits arranged close together. The ventral edges of the 
valves are fringed with a row of fine bristles. 
The eye is moderately large; the ocellus is about the 
same size, square in shape and situated nearer to the eye 
than to the tip of the rostrum. ; 
The antennules are short and thick, not nearly reaching 
the tip of the rostrum. . They bear a number of bristles at 
the tip. The antennee are small; in structure they agree 
with those of other species of the genus. The lip-plate is 
comparatively large and rounded. 
The tail-piece (fig. 8) is long and slender, slightly nar- 
rowed towards the apex. There are about fifteen pairs of 
‘spines present on the infra-anal margin, those nearer the 
end-claws being larger and stronger; above the anal spines 
is a row of marginal combs. The end-claws are very long, 
curved at the tips; a strong secondary denticle is present 
at the base of each reaching to half the length of the end- 
claws. 
This species agrees most nearly with the Australian form 
Alona archeri described by G. O. Sars in “‘Additional Notes 
on Australian OCladocera.’’®) It differs from the latter in 
the following details:—The sculpture of the shell has not 
the longitudinal rows of pits characteristic of A. archeri, 
the pits being massed together in an irregular manner. The 
ocellus is very much larger, square in shape and situated 
comparatively closer to the eye. The proximal spines of 
the tail-piece lack spinules on the upper edge; the lateral 
spines of A. archeri are replaced by combs in A. wallaciana 
and the secondary denticles at the base of the end-claws 
are longer and stronger. 
Specific Characters.—Carapace seen laterally is oblong . 
oval; dorsal margin arched, ventral edges straight, corners 
evenly rounded. Surface of the carapace marked with 
