AUSTRALIAN CLADOCERA. 



which is obliquely truncate. Free edges of valves deusely setose* 

 three of the setae affixed to the infero-posteal corners excessively 

 elongated and spreading. Posterior branch of shell-gland much 

 larger than anterior, reaching longitudinally beyond the middle 

 of the valves. Head large and thick, obtusely pyramidal, inferior 

 edge oblique and almost straight, not prolonged posteriorly in 

 any distinct rostrum; superior edge gently curved and uniting 

 the dorsal edge of the carapace, without any intervening sinus. 



Eye, as in Latona, located in the dorsal part of the head, at a 

 great distance from the optic ganglion. Ocellus immediately in 

 front of the base of the labrum, very minute. Flagellum of 

 antemmlae about three times as long as the basal part, finely 

 filiate. Upper branch of antennae with 12 natatory setse (5 on 

 first. 7 on second joint), the apical one very elongate; inferior 

 branch with five setae, one of the apicals almost twice as long 

 as the others. Tail rather small, generally not projected beyond 

 the valves, obtusely conical; anal denticles very minute. 9 on 

 each side; apical claws curved, with 2 strong secondary spines J 

 caudal setae rather elongate, originating from separate mammillar 

 processes. ' Body pellucid, without any distinct pigment. Length 

 of female reaching 1,60 mm. 



ft marks. — In the above diagnosis I have sought to adduce 

 some characters, which in my judgment should be regarded as 

 merely specific in value. Meanwhile, the present form being 

 the only species as yet known of the genus, it is of course rather 

 difficult to draw up at present a strictly specific diagnosis. 



Description. — The length of the largest female specimen 

 examined is 1.60 mm; most of the specimens were however con- 

 siderably smaller, scarcely exceeding 1,20 mm in length. In its 

 general form the body (see PI. 1, figs. 1, 2) is very similar to 

 that of Latona set if era Muller, being rather narrow oblong and 

 almost as broad as high. On closer examination, however, some 

 well-marked differences are found to exist. Thus, as seen laterally 

 (fig- 1), the head exhibits a more pyramidal shape, its inferior 

 edge running, with an almost straight course, obliquely upwards 

 to the region where the eye is located, whereas in Latona it 



