164 'PROCEEDINGS OE THE GEOLOGICAL SOCIETY, [June 15, 



P. Prinsepii, the young specimens of which at Takli are of the same 

 size as well as form. But if it be an adult, then it is obviously of 

 a different species ; and, as it approaches nearer to the modern dimen- 

 sions of the genus, I should be inclined to hold, that our intertrap- 

 pean deposit with its huge Physas falls under a division of Eocene 

 lower than the Nummulitic strata, in which it occurs. 



This latter conclusion would appear to be borne out when we 

 apply the per-centage rule to the solution of the problem. I have 

 shown my freshwater fossil shells to Mr. Benson, the highest autho- 

 rity on the molluscs of our Indian lakes, and he gives it as his 

 opinion that not one of the specimens submitted to him exactly cor- 

 responds to anything he has seen. I have had access to Mr. Cuming's 

 splendid series of marine shells, as well as to our National Collection, 

 and I have not been able to detect among the fossils from Raja- 

 mandri one existing species either from India or anywhere else. 



On the essential differences between the R-ajamandri shells and 

 those now inhabiting Eastern seas, it does not become me to speak, 

 as I have little personal acquaintance with our Indian coast ; but 

 my residence in the interior of the country afforded me opportunities 

 of observing the lacustrine molluscs of Central India, and I could 

 not help being struck with the marked distinction between the 

 ancient Testacea and those still existing there. The present Melanice 

 are much larger and stouter than their fossil congeners, and so 

 generally are our living Paludince and Limncece. And more than 

 this : Physa and Valvata, two genera of our rocks, have disappeared 

 from the Deccan, while Ampullaria and Planorbis, that have come 

 in their places, are not to be found in our strata. A change equally 

 great has occurred in the fishes, and one perhaps still more decided 

 in the Flora ; but on these I must not dwell, for I feel that this 

 paper has already extended to too great a length. 



And now I would desire to indicate, in as few words as possible, 

 the rocks to which I consider ours nearest in age. If the " Num- 

 mulitic" Physa of Northern India be too small to agree with the 

 P. Prinsepii of Nagpur, there is one on the continent of Europe 

 which is well nigh large enough — I mean the P. gigantea of Billy 

 la Montagne. At this Lower Eocene locality we find other shells^ 

 that may be allied to our slender Limncece — I allude to those re- 

 garded by De Boissy as Achatince. Again, coming to British strata 

 of Lower Eocene age, I would point out the similarity of our larger 

 fish from Dongargaum, our Lepidosteus ? scales, and our Pseudoliva^ 

 to remains found in the London clay. Finally, some of our fruits 

 bear a considerable resemblance to those discovered in the Isle of 

 Sheppey and contemporaneous deposits in Belgium*. 



From all these facts I am disposed to deduce the inference that our 



* While this paper is passing through the press, I have seen the vegetable 

 remains recently found in the clays of the Woolwich series in the neighbourhood 

 of Dulwich. They comprise specimens of those peculiar strobiliform fruits so 

 abundant at Nagpur and in Sheppey, which, beginning in the chalk as Carpolithes 

 Smithies, seem to have attained their greatest development in the Lower Eocene. 

 (April 2, 1860.) 



