114 Occurrence of recent Shells in the fossil state near Melbourne. 



when compared side by side, it is impossible to distinguish them 

 by the slightest difference ; and as this species, according to 

 Prof. Agassiz^s recently published opinion, includes the Sheppey 

 London-Clay C. Toliapicus amongst other varieties, I need only 

 say that the best-marked Eocene and Miocene varieties found in 

 Europe and America are perfectly represented, on comparison 

 of specimens, by the different varieties in our Bird-Rock Bluff 

 beds. 



It is, I think, a very curious result of the careful comparison 

 I have made between the fossil species of the Bird- Rock Bluff 

 Mollusca and their nearest allies, that I can with certainty an- 

 nounce one of the commonest of them to be specifically identical 

 with the Limopsis Belcheri of Adams and Reeve, of which the 

 few known specimens were brought up alive from a prodigious 

 depth by Admiral Belcher, off the Cape of Good Hope. The 

 identification, I should say, does not rest on an examination of 

 the published figure and description, which would not have been 

 sufficient for the purpose, but, having been fortunate enough to 

 procure a living specimen for the National Museum which I 

 take a pleasure in forming during my residence in Melbourne, 

 I have perfectly satisfied myself of the complete identity of our 

 Miocene Tertiary abundant shell with the hitherto very rare 

 recent one by direct comparison. 



The Limopsis aurita (Sassi), perfectly identical with specimens 

 which I have used for comparison from the Coralline Crag 

 of Suffolk and many Miocene localities in Germany (which 

 Mr. Jeffreys has lately dredged from 85 fathoms off Unst, in 

 Shetland), is also common, though not so abundant in the 

 Australian beds as the L, Belcheri. 



The third living species of the Arcidce in these .beds is the 

 Pectunculus laticostatus (Quoy & Gaimard) of New Zealand, 

 occurring just as abundantly as the others. 



The last bivalve I shall mention in this communication is an 

 extremely abundant Corbula, which I can safely pronounce 

 identical with the C. sulcata now living on the west coast of 

 Africa. Lest it might be supposed that, judging from figures 

 or descriptions, I had mistaken the North-east Australian Cor- 

 bula tunicata or other allied forms for the C sulcata, I should 

 state that this is not so, but that, in working out the palseonto- 

 logy of our Australian deposits, I have thought it my duty to 

 science to take the precaution of procuring every recent species 

 I refer to for comparison before assuming an identity. 



The commonest Dentalium in these beds I believe to be a 

 mere variety of the Upper Eocene D. Mississippiensis (Conrad) 

 from Vicksburg. 



Melbourne, May 25, 1865. 



