87G 



THE EFFECT OF THE BASSIAN ISTHMUS UPOX 

 THE EXISTING MARINE FAUNA: A STUDY IN 

 ANCIENT GEOGRAPHY. 



By C. Hedlky, F.L.S. 



The marine molluscca of Western Port and Port Phillip in 

 Victoria have been carefully examined by Messrs^. G. B. Pritchard 

 and J. H. GatlifF. The results of their work appear in an 

 admirable Catalogue published in parts by the Royal Society of 

 Victoria, and now approaching completion. If this fauna be 

 compared with the marine moUusca of South Australia as reflected 

 in the writings of the late Prof. Tate, it will be found to be in 

 essential points the same. I have lately been favoured by my 

 friend ^Nlr. A. U. Henn with a small l)ut important collection 

 illustrative of the molluscan fauna of Geraldton in 29° S. lat. in 

 West Australia 



Though here the Melbourne fauna commences to fade away 

 and to be masked by the overlap of species characteristic of the 

 tropical Indian Ocean, 3'et it is still recognisable. So the same 

 fauna extends from Melbourne westward for 2250 miles to sub- 

 tropical West Australia. 



In the expectation of meeting at least some traces of the 

 Melbourne fauna, I once devoted some days to collecting at 

 Twofold Bay in southern New South Wales. Though at this 

 point Melbourne is only distant about 450 miles along the coast, 

 its fauna is quite absent. One misses, for instance, the large and 

 handsome Phasianella aicstralis, abundant on every beach along 

 the whole south and south-west coast of this Continent. As the 

 smallest fragment of this beautiful shell is readily recognisable, 

 the absence of the species from the east coast of Australia is a 

 matter of certainty. 



