BY J. C. COX, M.D., r.L.s. 127 



purple ; liinge acuminated, sides crenulated near the hinge. The 

 sculpture of the shell is bold and large, and the square character 

 of the ventral margin is striking." 



The habitat given by Keeve is Australia. 



This undoubtedly is our drift oyster, dredged so abundantly 

 in beds at the mouths and in the channels of the rivers empty- 

 ing themselves on the East Coast, and now so valuable an article 

 of export from this city to the neighbouring colonies. 



Ostrea sultrigona of Sowerby may justly be placed as the second 

 species of importance —if it should not take first position — found 

 in the Australian waters, it is the '' drift oyster " of the harbours 

 of New South Wales, the oyster in most common use as an 

 article of food throughout the whole of New South Wales, and 

 largely exported to Melbourne, Adelaide, Brisbane, Tasmania and 

 even New Zealand and Fiji. 



It is difficult to account for the absence of this abundant 

 and valuable species in the list of Conchifera from Port 

 Jackson and the adjacent coasts as published by Angas in 1867, 

 I can only conclude that he considered it one and the same 

 species as our rock oyster, which he erroneously considered 

 Ostrea mordax of Gould, whereas it really is Ostrea glomerata of 

 Gould. This species has attained the name of Drift Oyster on 

 the supposition that the beds which it forms itself into are 

 shifted from one part of the bay or river to another by the 

 influence of tides or storms ; these so-called beds are composed 

 for the most part of free unattached individuals, or attached in 

 masses to drift matter, or to each other by slight adhesion of 

 the lower valve. It is always found in moderately deep water 

 in beds well out in the stream and is never uncovered by the 

 fall of the tide ; it lives in a zone considerably below the zone 

 occupied by the Mud Oyster and Eock Oyster. 



It is popularly supposed, and believed that this and our common 

 Eock Oyster are one and the same species, so confident are some 



