19 



The total number of known South Australian polyzoa is thirty-five. 



Class Tcjnicata. — Quoy and Gaimard describe and figure fourteen 

 species of simple and compound ascidians from the south-west and 

 south-east coasts of Australia. Some of these will doubtless be found 

 to form a part of the comparatively rich tunicate-fauna of our shores. 



Land and Fresh-Water Mollusc a. — A special work on the Land 

 Snails of Australia exists as (t)" A Monograph of Australian Land Shells," 

 by Dr. Cox, published in 1868. The figures of some of the South Aus- 

 tralian species are not accurate, and the diagnoses are not always suffi- 

 ciently full. The number of South Australian Helices published in 

 Dr. Cox's monograph is twenty-two ; but since then additions have been 

 made, which make a total of thirty-four. Mr. Angas describes six in 

 Proc. Zool. Soc. for the years 1868, 73, 75, 76, and 77 ; Mr. Brazier 

 two in the same journal for 1871 and 1872, and a third in Free. Lin. 

 Soc , N. S.W., vol. 1., 1875 ; and I have made known three other forms 

 in Proc. Lin. Soc, N.S.W., vol. 2, 1878. No advance has been made in 

 the numbers of species of the other genera constituting our terrestrial 

 molluscan fauna. I think that a revision of our species is needed, but 

 efore considering the claims of several to specific rank it will be desir- 

 able to have more information respecting their distribution. Most of 

 our land snails are, according to book knowledge, very restricted and 

 each is more or less isolated. If this be really so, then we should seek 

 to establish a connection between their isolation and the development 

 of that character proper to each. 



No attempt has been made to bring together in a monograph the 

 scattered sources of information concerning the fresh water mollusca of 

 Australia. But the Rev. J. E. Tenison Woods has arranged the fresh 

 water shells of Tasmania, vide, "On the Freshwater Shells of Tas- 

 mania," (Proc. Roy. Soc. Tasmania), 1876 ; of which there are 28 uni- 

 valves and four bivalves, the majority being described as new to science,, 

 Woods in 1875 held the opinion that this part of the Tasmanian fauna 

 is perfectly distinct from that of Australia, and that its facies or general 

 character is not Australian : but two years later, when describing some 

 new freshwater shells inhabiting Victoria (Trans. Roy. Soc. Vict, 1878A 

 he takes an opposite view. The freshwater shells of Australia and 

 Tasmania have a common character, and many of them are widely dis- 

 tributed, being common to several hydrographical areas. The identifi- 

 cation of the South Australian species will involve considerable labour 

 as all the Australian freshwater shells and their animals must be re- 



