208 NERBUDDA DISTRICT. 



supposition were correct. In every case within our experience, the sedi- 

 mentary beds have been deposited tranquilly on the previously indurated 

 and moreover previously denudated surface of the trap rock ; and in several 

 cases a large portion of the material constituting these sedimentary beds 

 is derived from the debris of the trap flows themselves. 



Mr. Hislop further arrives at the conclusion that these " intertrap- 

 pean " beds are of the same era as the so called ' ' Diamond Sandstone." 



It is, we think, to be regretted that this name should be retained, even 

 provisionally, as indicative of a geological sub-division ; inasmuch as it 

 is almost certain that beds of very different ages have been described 



We do not desire to question the accuracy of these observations, although it does at first 

 appear strange that such comparatively delicate freshwater shells as Physa shall be well 

 preserved, associated with heavy and massive marine shells such as Cardita, Perna, Ostrea, 

 Cytherea, Psammobia &c. 



But we would certainly venture to suggest a careful examination of the localities. 

 Amono- a collection of shells from this deposit near Eajahmundry, procured through the 

 kindness of the Hon'ble Walter Elliot, of Madras, and containing some thousand individuals 

 representing about 20 species, there is not a trace of a freshwater shell, and we think it just 

 possible that the distinct deposits have been found in close superposition, and have been 

 hastily taken as one and the same. That there should be a gradation from pure freshwater 

 and lacustrine deposits on the west to estuary deposits towards the east is at the same time 

 by no means improbable. 



Up to the present time Mr. Hislop has published only a list of names of species from these 

 intertrappean beds, in which he gives the following, Melania, (2), Paludina, fl2), Valoata, 

 C4) Succinea (1), Lymnaza, (5) Physa, (2), Unio, (6), — in all 32 species with two varieties. 

 Our specimens would lead us to results somewhat different, and this difference is of consider- 

 able importance as bearing on the nature of the deposit, inasmuch as we are led to believe that 

 several of our shells belong to different genera, and that they are land rather than freshwater 

 shells. We give a list also, of what our collections contain, Melanin, (1), Paludina, (6,), 

 Valvata, (3), Lymncea, (7), Physa, (3), Achatina, (7), Unio (1) (?2), Cyclas, or Pisidium(\),— 

 in all 30, with 2 or 3 varieties, These have all been named and described for some time 

 but not published. Por the reasons given above any detailed account of them is now withheld. 



We would add here that we have for some time had very strong doubts that some of 

 the shells derived from localities in the vicinity of Nagpur really belong to this "Inter- 

 trappean group at all. The general constancy in mineral character of these beds wherever 



