70 



long time after, and the whole volume in which it is incor- 

 porated did not appear nntil 1877. 



I should remark, also, that Professor Tate has forwarded 

 me many shells, collected by him in South Australia and 

 Western Victoria, which come so very close to our Tasmanian 

 species that, except in point of size and color, I really could 

 not see any difference. Knowing what a very wide distri- 

 bution our freshwater shells have in Australia, and how 

 many I have found common to Tasmania and Victoria, I 

 very much question if the whole of the species may not have- 

 to be reduced to one or two. But this should not be done 

 until the animals have been carefully observed. The mere 

 resemblance of shells is not sufficient, for, as Mr. J. E. G-ray 

 lias well observed, shells in every way similar may belong to 

 totally different genera. He says — " About 15 years since I 

 first observed, in the marshes near the banks of the Thames, 

 between Greenwich and Woolwich, in compraiy with species 

 of Valvata, Bythinia and Pisidium, a small univalve shell 

 agreeing with the smaller species of the littoral species 

 Ziiitorina, in every character tjoth of shell and operculum. 

 Yet this very peculiar and apparently local species has an 

 animal which at once distinguishes it from the animal of that 

 genus, and from all other Ctenobranchrous mollusca. Its 

 tentacles are very short and thick, and have the eyes placed 

 at their tips, while the LiUorincv-, and all other animals of 

 the order to which they belong, have their eyes placed on 

 small tubercles on the outer side of the base of the tentacles, 

 which are generally more or less subulate. " Taking this in 

 conjunction with the preceding, we have here instances of 

 univalve shells apparently belonging to the same genus, the 

 one found in fresh, the other in salt, water, proving, when 

 these animals are examined, to belong to genera essentially 

 distinct."* He also gives similar instances among the 

 bivalves. I may add that in making an examination of the 

 animals of some of our land shells, with the aid of the expe- 

 rience of Dr. J. Cox, and the excellent drawings in his 

 possession, I find that shells which I certainly regarded as 

 no more than varieties are really Cjuite different in the 

 animals. It must, therefore, be only after a careful exami- 

 nation of the shells and animals here named that any altera-^ 

 tion of the list should be determined upon by future 

 observers. 



Since the jjublication of my paper in the j^roceedings of 

 this Society I have described a very small one in the pro- 

 ceedings of the Eoyal Society of Victoria, which was read 

 August 9, 1877. It is a small species from Lake Connewarre, 



* Philosophical Transactions, 1835, part 2, p. 303. 



