Art. XII. — Description of a New Sjjecies of Unto from 

 tJie River Glenelg. 



By J. Dennant, F.G.S. 



[Eead 12th August, 1897.] 



(Plate IV.). 



About twelve years ago I picked up on the banks of the 

 Olenelg at Dartmoor a few worn valves of a Ufi/o markedly 

 differing in outline from the well-known [/. aiistralis^ which 

 is abundant in that stream as well as in most others of the 

 colony. No other specimens were met with from that time 

 till the Christmas Vacation of 1895, when a holiday trip took 

 me to Eoseneath, many miles higher up the same river. 

 Several examples were there gathered, but all as dead shells, 

 and though the friend whom I was visiting dived and searched 

 the mud at the bottom of the river for living ones, he was 

 unable to find any. He has, however, since sent me a young 

 one which has a perfectly fresh appearance. Examples of the 

 shell have also been forwarded- to me by the Rev. W. Whan, 

 but they are from the same locality, viz., Roseneath. 



This Unio possesses characteristic features which distinguish 

 it from all other Australian species known to me, either 

 by actual examples or from published plates and descriptions. 

 I take this opportunity of acknowledging my great indebted- 

 ness to Dr. James Cox of Sydney, who has kindly furnished 

 nie with a fine collection of the Unios of New South Wales. 

 The following is the diagnosis of the species : — 



Unio gleneigensis, spec. nov. 



Shell ovately sub-rhomboidal, sub-depressed, inequilateral, leng- 

 thened posteriorly ; anterior side short and together with the 

 ventral edge regularly curved ; posterior dorsal margin straight 

 along hinge line, and then sharply sloping downwards by a 

 slightly sinuous line to the roundly pointed posterior end ; 



