338 On the Structure of the Delta of the Ganges. 



formed of the debris of primary rocks, imbedded in an arena- 

 ceous matrix. The fossils of the upper bed, which is about 

 eighty feet in thickness, furnish the only specimens of the 

 bones of mammalia obtained during the operations. These 

 were associated with the remains of Chelonians, but no indi- 

 cations of the existence of Saurian animals were discovered 

 till the shelly clay and carbonaceous bed were passed 

 through, and from the lower conglomerate no mammalia were 

 obtained. It is necessary, however, in thus stating in gene- 

 ral terms the distribution of the Fort fossils, to recall to 

 mind the extremely limited foundation on which such con- 

 clusions rest. A space whose diameter was no more than 

 six inches, has furnished all the specimens described, and 

 though this circumstance may be deemed a strong proof of 

 the great abundance of such treasures in the strata penetra- 

 ted, it can warrant inferences as to their general distribution 

 and association only of the most limited range. It is, how- 

 ever, interesting to find that the conclusions drawn from the 

 Fort fossils are to a considerable extent supported by the 

 distribution of the remains in other localities which are pro- 

 bably of the same geological age as the lower deposits of the 

 Gangetic Delta. Thus in describing the succession of 

 strata, and the distribution of the fossils in the pass of Amb- 

 walla, of the Sub-Himalayan series, Captain Cautley states,* 

 " There are here three grand deposits ; first, the lower with 

 lignite, consisting of a coarse conglomerate full of remains, 

 highly impregnated with hydrate of iron, the leading ones 

 being Saurian and Chelonian, but abounding in bones and 

 teeth of mammalia, vertebra, and teeth of fishes, and a few 

 shells, but the latter are very imperfect and broken — their 

 thinness would probably prove them fresh water. Second, 

 the blue marl or clay filled with the fresh water shells 

 above mentioned. Third, the upper, or grand deposit of the 



* Asiatic Society's Journal, vol. vii. 



