BY MARGUERITE HENRY. 37 



Distribution. — ^This species is here recorded in Australia for the first time; 

 it has only been obtained from Casino, N.S.W. It also occurs in Ceylon and 

 South America. 



Genus P s E u d ii I N a Sars, 1912. 



Carapace of irregular oval form with the valves well developed and ' com- 

 pletely enclosing the body. Head defined by a well marked cervical sinus. 

 Labrum bearing a slender digitifoi-m process. Ocelliis present. Antennules 

 slender, straight. Each ramus of the antennae bears five setae. Five pairs of 

 legs. Post-abdomen devoid of anal denticles; end-claws strong. Intestine 

 straight, caeca absent. Only one species known. 



P.SEUDOMOIXA LEMNAE (King). 



First described by King (1852, p. 250) as Moina letmiae. Sai-s redescribed 

 it and proposed a new genus in 1912 (Plate 10, figs. 1-16). 



Female. Carapace, seen laterally, somewhat oval; dorsal margin almost 

 straight, ventral edges curved, thickly clothed with long setae, posterior edges 

 narrowly rounded, partly clothed with setae, the last six or seven of which are 

 long and spr-eading. Head rounded in front, rostrum very slight. Eye large, 

 ocellus very small. Antennules narrow, elongated, bearing short bristles through- 

 out their length. Upper ramus of the antennae composed of four segments, the 

 first of which is very small. Process of the labrum slender, recurved, bearing 

 bristles on the anterior edge. Surface of the carapace perfectly smooth. Post- 

 abdomen bearing slender spines on the supra-anal margin; end-claws strong, 

 curved, a secondary denticle at the base of each. Length 1.2 mm. 



Male. Smaller than the female. Antennules comparatively longer; first pair 

 of legs armed with a claw. 



Distribution. — N.S.W. : Cook's River, Holbrook, Kendall; Victoria. 



Genus Iltoceyptus Sars, 1801. 



General form oval-triangular, dorsal crest of valves absent or small. An- 

 tennules long, 2-jointed, freely movable. Antennae short, with powerful setae. 

 Eye small but larger than the ocellus. Six pairs of feet. Post-abdomen very 

 large, with long spines; end-claws with two basal spines. 



Male. Larger antennules than the female, no hook present on the first foot. 



Unlike the other members of the Cladocera the old shells of most species 

 are not cast off in moulting but pei-sist, one overlying the other. The members 

 of this genus are not strong swimmers, and are usually found in the bottom 

 mud, their shells covered with debris and vegetable growth. Seven species are 

 known, two of which are present in New South Wales. 



Key to specie's of Ilyocryptus. 



A. Antennae large and powerful spinifer. 



A.'^. Antennae small sordidns. 



Ilyocryptus spinifer Herrick. (Plate vi., figs. 1-la.). 



{Syn. I. halyi Brady; I. longiremus Sars.). 



This species was first described by Herrick in 1884. 



Female. Carapace, seen laterally, triangular, much wider posteriorly; ven- 

 tral and posterior edges of the valves passing into each other with an even curve, 

 dorsal and posterior edges forming an obtuse angle. In old specimens the cara- 



