the Eastern Portion of the Basaltic District of India. 569 



(as every thing indicates) to the same formation. I am indeed of opinion, 

 that the argillaceous limestone and the sandstone constitute only one forma- 

 tion, although I do not think that they should be spoken of as such in the pre- 

 sent state of our knowledge. The basalt which has broken up and penetrated 

 these rocks to the north and south of the Nerbudda, is connected with the same 

 system of trap rocks, and was probably erupted at a period much more recent 

 than either of those to which the sandstones and limestones have been referred. 



Inferences respecting the Freshwater Fossils. 



On the evidence on this subject afforded by the fossils imbedded in or 

 covered by the basalt, I shall now make a few observations. For the de- 

 scriptions of the shells, I am indebted to Mr. J. De Carle Sowerby*. 



These fossils all belong to freshwater genera, and to species which have 

 not yet been discovered recent. I have not been able to obtain the seeds of 

 Asiatic Charce, nor the valves of any Ci/pris inhabiting the fresh waters of 

 India. The shells, however, all differ from those inhabiting the rivers of the 

 neighbouring country, as far as Mr. Sowerby and myself could judge, by com- 

 paring them with a collection of recent shells, which T made during a residence 

 of several years at Nagpoor ; nor do I think it possible that any of the larger 

 shells could have escaped my notice, did they still inhabit the northern branches 

 of the Godavery. Colonel Sykes, also, had the kindness to allow me to exa- 

 mine a collection of recent shells made by him near the western ghats, 

 consisting of the same species as those of the Berar valley, and they are of 

 course different from the fossils. I also failed to detect amongst them any 

 of the shells contained in a large collection of recent land and freshwater 

 Testacea from Bengal, presented to the Zoological Society by Mr. Benson. It 

 may therefore be inferred, that the fossils do not belong to recent species. 



Gyrogonites have not yet been observed in any deposit more ancient than 

 the freshwater formations of the basin of Paris. Cyprides occur in the ter- 

 tiary strata, and in the Weald clay below the chalk, and perhaps in the Birdie- 

 house limestone of the Edinburgh coal-field. Of the other five genera dis- 

 covered in these fossil beds, two have hitherto been found only recent or in 

 tertiary deposits, viz. Limnea and Physa ; and the best characterized speci- 

 mens of some of the others are referable to the same period. It is therefore 

 extremely probable, that the basalt in which these fossils are imbedded, and 

 which has altered the rocks in which they occur, belongs to the tertiary epoch ; 

 but to which period, I fear we have not the means of forming any decided 

 opinion. Though none of the species are recent, yet they are too few and in 



* See Plate XL VII. and Description. 



