1888.] AUSTRALIAN CLADOCEEA. 29 



orly to a broad triangular prominence, generally covered by the 

 valves. 



The mandibles and maxillae exhibit the usual structure. 



As to the structure of the legs, that of the anterior pairs 

 at least would seem on the whole to be on the Lyuceid type, 

 the 1st pair being by far the largest and terminating with se- 

 veral strongly denticulated spiniform setae, partly projecting be- 

 yond the valves. The 4th pair is prominently distinguished by 

 the extraordinary size of the vesicular appendage (epipodite), 

 whereas the lamellar appendage (exorodite) is wholly rudimen- 

 tary. Finally, I have failed to detect any trace of a 5th pair 

 of legs; if notwithstanding they should prove to be present, their 

 condition must in any case be extremely rudimentary. 



The tail (fig. 4) is comparatively very small, and is gene- 

 rally strongly inflexed, in such manner that its terminal part 

 remains hidden between the posterior legs. On separating the 

 tail by dissection, this terminal part appears very short and 

 somewat instricted, with the caudal claws unusually small and 

 feeble; below the latter the dorsal edge forms a somewhat pro- 

 jecting curve, and to each side of this curve a few small spines 

 are affixed, representing the anal denticles. Posterior to the 

 above-mentioned convex part there is a slight sinus, whereas the 

 remaining part of the edge is evenly curved and armed with a 

 single regular series of rather strong denticles, giving it a 

 densely serrate appearance. The caudal setae are rather elongate 

 and divergent, nearly as long as the tail, Particulate, with the 

 1st joint very t elongate and quite smooth, the 2nd unusually 

 short and provided with long and delicate cilia on both edges. 

 They originate close together from a common, very slightly pro- 

 jecting rounded prominence, at the upper end of the dorsal edge. 

 — At some distance above this prominence the dorsal part of 

 the body forms a triangular setose projection, which generally 

 lies in close contact with the extremity of a rather broad inner 

 fold running along the dorsal edge of the carapace. More an- 

 teriorly the dorsal part of the body exhibits (see fig. 1) in gra- 

 vid female specimens 4 peculiar mammilliform processes pro- 



