BY PROFESSOR RALPH TATE AlfD JOHN BRAZIER, C.M.Z.S. 553 



Our experience in the literature is such as induces us to urge, 

 that a systematic effort be made to revise the whole nomenclature 

 relating to the subject. Australian naturalists are, we think, 

 all agreed that a work of this kind can be efficiently undertaken 

 by ourselves ; and as this Society, in its corporate capacity, is 

 more capable of securing co-operation, than an individual is, we 

 would suggest, in the above connection, that it take the initiatory 

 steps. 



In the accompanying list, we have refrained from critical 

 remarks of our own ; but have tentatively accepted those which 

 have been published by others. Therein, we have endeavoured 

 to arrange the species so as to indicate their alliances ; the 

 localities given are those appended to the original diagnoses, 

 excepting in such cases where previously none had been known 

 a locality has since been found. In the Unionidce we have 

 largely availed ourselves of Mr. Etheridge's list of the Recent 

 Australian Species in Rep. Depart. Mines, N.S.W., 1878, p. 165. 



We would call attention to the fact that the animals of nearly 

 all the species have not been examined, and in consequence the 

 systematic position of many has merely been guessed at. If 

 the distinctions between Phjsa and Amplexa, Lymncea and 

 Aniphipeplea, Ancylus and Velletia, &c, are to be maintained, 

 then is there the greater need for this kind of investigation. 

 Personal examination in this direction has elicited the fact that 

 species described as Phjsa and Amphipeplea are wrongly referred 

 to those genera. Particularly among the fresh-water Rissoidce 

 does much generic confusion prevail. 



The result of the present compilation, so far as numbers are 

 concerned, is as follows : — 



Lymnsea . . . . 16 



Physa . . . . 54 More than half for the whole world. 



Physopsis . . . . 1 



Ancylus . . . . 4 

 U 



