1888.] AUSTRALIAN CLADOCERA. 59 



motion is anything but active, and affected by rapidly repeated 

 strokes of the antennae, propelling the animal through the water 

 at quite a uniform rate, the belly generally upwards. The ani- 

 mals seemed in particular to affect the side of the aquary ex- 

 posed to the rays of the sun. Here they were often found con- 

 gregated in great numbers clinging to the walls of the aquary 

 or to algae growing there. 



Occurrence. — Also this form was raised from the same 

 parcel of mud, that yielded the preceding species of Lynceidae, 

 though not developed in the same aquary. Hence the only loca- 

 lity as yet known for the present species is the above mentioned 

 Water Hole at Cattle Station. 



11. Alona laevissima, n. sp. 



(PI. 6, figs. 5-6). 



Specific Characters. — $. General habitus very like that of 

 the preceding species. Carapace, as seen laterally, oblongo- 

 quadrangular in form, posterior part truncated, with upper angle 

 distinct, lower rounded; inferior edges of valves nearly straight. 

 Head about as in A. Archeri, Surface of shell quite smooth, 

 without any trace of sculpturing. Ocellus nearly as large as 

 eye. Antennuhe rather narrow, reaching almost to the tip of 

 the rostrum. Tail comparatively shorter and broader than in 

 the preceding species, transversally truncated at the tip. supra- 

 anal angle very slightly projecting; outer part of the dorsal 

 edge armed; with a double series of rather small denticles, the 

 outer a trifle larger than the rest, but quite smooth; a lateral 

 series of 5 lamellar appressed denticles present; caudal claws 

 rather strong, with a slender secondary denticle at the base. 

 ( ( >lour clear yellowish or corneous. Length of adult female 

 0.48 mm. 



Remarks. — At first I believed this form to be identical 

 *'ith the: species described by King under the name of Alona 



