226 Proceedings of tJie Royal Society of Victoria. 



The present paper describes four new species, all Victorian 

 fresh- water inhabitants, for one of which I have thought it 

 necessary to form a new genus, which embraces also Thomson's 

 Niphargus montanus from Tasmania. 



I desire to acknowledge my indebtedness to Mr. G. M. 

 Thomson, F.L.S., of Dunedin, for furnishing me with co-types of 

 his Tasmanian species, to Professor Baldwin Spencer, F.R.S., 

 for a few specimens that he had collected from Lake Petrach, 

 Tasmania, and also to Messrs. J. Shephard, J. Gabriel and C. 

 Barber for specimens collected from this colony. 



Family ORCHESTIDAE. 

 Hyalella australis, sp. n. 



(Plate XXXVI.). 



Male. — Body smooth, back deeply arched. Cephalon longer 

 than first segment of mesosome, lateral corners broadly rounded, 

 and slightly projecting between the bases of the antennae. Eyes 

 large, slightly oval, black. Side plates of iirst and second 

 segments of mesosome deeper, those of third and fourth equal to 

 their respective segments. Second and third segments of meta- 

 some with infero-posterior angles acute, very slightly produced 

 backward. 



Upper antennae very long, measuring half the length of the 

 body, flagellum of about ten articuli, longer than its peduncle. 

 Lower antennae shorter than the upper, its peduncle reaching 

 slightly beyond the peduncle of upper, flagellum of about seven 

 articuli. First gnathopoda short, hind margin of carpus slightly 

 lobed, with the margin evenly rounded, and fringed with about 

 nine delicately feathered setae ; propodus sub-trigonal, longer 

 than the carpus, palm straight, oblique, defined by a small spine, 

 margin seto.se. Second gnathopoda long, with the carpus small, 

 not lobed, and free from seta?, propodus large, almost as long as 

 the basis, subovate, narrowing distally, palm very oblique, of 

 even length to the joint's greatest width, slightly convex, and 

 defined l)y a small rounded tubercle, margin spinose. Dactylus 

 falciform, margin entire. Third and fourth pairs of peraeopoda 

 with the bases expanded in a lesser degree than the fifth, 



