80 ME. GEOFFREY WATKIN SMITH ON THE 



Subclass ENTOMOSTRACA. 

 Order PHYLLOPOBA. 



Family Apodidje. 

 Genus Lepidubus. 



Large numbers of the common L. viridis, Baird (see also Sayce, Proc. Roy. Soc. 

 Victoria, xv. 1903, p. 242), were taken in a small roadside pond near Bridgewater, on 

 the Berwent. 



Only the genus Lepidurus is represented in Tasmania and Southern Australia, Apus 

 being entirely absent. Lepidurus, on the other band, is altogether absent from Northern, 

 Central, and Western Australia, where it is replaced by Apus. 



Family Dapenida 



Genus Ceriodaphnia (Bana). 



The species described below agree with the northern Ceriodaphnia closely in their 

 appendages, but differ considerably in the general form of the body. C. cornuta (Sars, 

 Forhand. Videns. Selsk. Christiania, 1885), the only other Ceriodapbnid from Australia, 

 seems to be closer to the northern species. 



Ceriodaphnia hakea, sp. n. (PI. 15. figs. 10-16.) 



Female. — The form of the carapace is rounded, and there is no posterior spine, only a 

 slight angle. The constriction between the thorax and the head is not very sharply 

 marked. The head bears dorsally a remarkable recurved hook, a character not known 

 in any other member of the genus. The outline of the head is regularly curved and not 

 in the least sinuous. There is no spine or tumescence on the head in front of where the 

 first antennas spring from. 



The ocellus is very clearly marked. 



The first antennae carry very short terminal setae, and a fairly long single seta on a 

 ridge some distance away from the apex. 



The distal joint of the second antennae bears only Wo compound plumose setae 

 (PI. 15. fig. 15). 



The anal claws are long and are not furnished with any small spines ; behind the 

 claws the telson bears laterally five large spines decreasing in size anteriorly. Between 

 the anal claws and the two plumose setae on the back, the hind end of the body is 

 regularly arched without any distinct angulation or sinuosity (PI. 15. fig. 14). 



Length 1 mm. 



Colour. Green. 



Occurrence. In the plankton of Lake St. Clair. No males were observed. 



