HISLOP AND HUNTER NAGPUR. 375 



the whole thickness of the highest beds may be reckoned at about 

 200 or 300 feet. At Kota, as we have seen, it ranges from 50 to 

 500 feet, at Mudalaity 120 feet, and at the Mahadewa hills, accord- 

 ing to Mr. Sankey, 2700 feet, which must be its greatest develop- 

 ment, c. The depth of the shales at Korhadi and Tadac?! seems to 

 be — green about 30 feet, red 50 feet. At Kota, omitting inter- 

 stratified argillaceous limestone and sandstone, all the argillaceous 

 thin strata united amount to 29 feet, red clay 27 ; while at Newbold's 

 section of Mudalaity, where the shales, usually reddish, underlie the 

 limestone, they attain a thickness of 50 feet. d. The limestone 

 which underlies the shale has been much disturbed by granite at 

 Korhadi, so that we cannot fix its thickness precisely ; but I should 

 think it cannot be less than 100 feet — at Mudalaity it is 360 feet. 

 Under this limestone, which is included in Dr. Carter's excellent 

 paper, along with shales and coal under the name of Kattra shales, 

 there occurs, as Newbold has shown in Southern India, and Franklin 

 in Bundelkhand, another series of sandstone rocks, for which Dr. 

 Carter proposes the name of Tara sandstone ; but, as most probably, 

 owing to the intrusion of the granite, this member of the formation 

 does not occur in our neighbourhood, I have nothing to say re- 

 garding it. 



Character of the Formation. — There can be little doubt that the 

 upper strata are lacustrine. The occurrence in them of such an im- 

 mense collection of terrestrial vegetation, intermingled with Poacites^ 

 taken in connection with the total absence of Fucoids and other 

 marine plants, shows very plainly that they must have been deposited 

 in fresh water. And, as no river could have covered the extent of 

 surface which these beds occupy, we are bound to conclude that, 

 like the tertiary rock previously described, they must have been 

 formed in a lake, a conclusion which the discovery of Estheria (or 

 Limnadia), with their two valves entire, and congregated together as 

 they are found in their usual haunts, fully justifies. Again the 

 abundance of worm-tracks and borings in the red shale of Korhadi 

 and the green shale of Tada</i renders it more than probable that 

 the strata at these localities constituted the margin of an ancient 

 lake and not of a sea or even of a river. Of the origin of the dolo- 

 mitic beds it is impossible to give any certain account, owing to the 

 transformation which they have undergone, though we may suppose 

 they follow the analogy of the other members of the formation. The 

 character of the upper strata at Elichpur, as would appear from the 

 fossils discovered by Dr. Bradley, is exactly the same as at Nagpur. 

 The Lepidotus which has been found at Kota, from its association 

 with terrestrial vegetable remains, has been pronounced to have been 

 probably an estuary or inshore fish ; but, as the genus also occurs 

 abundantly in the freshwater strata of the Wealden, it may be per- 

 ceived that the strata at Kota are not of a different origin from those 

 in our neighbourhood. This supposition is rendered more likely by 

 the fact, that, while no marine vegetation is said to have been de- 

 tected there, a piece of the shale which Dr. Bell kindly sent me bears 

 the impression of a bivalve exceedingly like a Cyrena or Cydas. Dr. 



