Notes on Geology and Mineralogy of Afghanistan. 569 



sisting on the left of thick beds of shales and clay, and the 

 right of nummulite rock. 



In the bed of the Pass at this place, but not in situ, I 

 found several masses of indurated marly clays containing 

 beautifully preserved specimens of fresh-water shells ; some 

 of these blocks were composed of yellowish sandy clay, con- 

 taining shells of the genera Planorbis, Melania, Paludina and 

 Cyrena, intimately mixed up together ; and Mr. Benson, to 

 whom I lately submitted specimens, thinks he can recognise 

 some of the shells as still living in India, viz. Planorbis in- 

 dicus, Melania pyr amis t and Melania elegans ;* other blocks 

 were composed of hard bluish marl, and contained fine spe- 

 cimens of bivalves closely allied to, if not identical with, the 

 genera Unic and Cyrena. A lengthened search, on my re- 

 turn through the Pass from Candahar in 1841, failed to dis- 

 cover from what locality these blocks had been torn, and I 

 feel inclined to believe that they must have been swept 

 into the Pass from some of the lateral glens, which open and 

 drain into it. Their occurrence however is important, as 

 tending to confirm an opinion which the presence of the 

 deep beds of conglomerate and sandstone at the lower end 

 of the Pass had already given rise to, namely, that they 

 belong to strata of the tertiary formation, and I have since 

 had further reason to rely on the correctness of that opinion, 

 from finding no difference between the sandstone of the Pass 

 and the fossilliferous sandstone of the Siwalik range ; while 

 moreover I have been informed by Dr. Falconer, to whom I 

 showed specimens of the bivalves, that a fossil very similar 

 to them, and imbedded likewise in a bluish marl closely 

 resembling the matrix of the Bolan specimens, had been 

 found in the tertiary strata of the Siwalik range. 



Proceeding onwards towards Sir-i-Bolan and Sir-i-Kujoor, 

 the shales and indurated clays of the coal formation pre- 



* At Dadur I took living specimens of Melania pyramis, and in April 1839, the 

 stream at Beebee Nanee abounded with Melania elegans; but in the end of Fe- 

 bruary 1841, I could find no trace of a single shell. 



