INTRODUCTION. 17 



merate, and in some places the surface of exposed conglome- 

 rate is seen to be patched over with portions of a thin very 

 crystalline carbonate of lime, simulating very much the 

 appearance of portions of compressed marine bivalve shells, 

 which I at first suspected them to be. They have a round, 

 conchoidal surface, and a suitable thickness ; but I have seen 

 no specimen possessing unequivocal characters by which it 

 could be referred to a shell. 



Organic Remains. — The existence of coal or lignite in the 

 Sewalik hills has been known since the Goorka war, and has 

 led at different times to the idea that it might be found in 

 sufficient quantities for mining speculation. Cautley and 

 Herbert have described the circumstances under which it is 

 found, and the latter has given a detailed accoiant of its dif- 

 ferent varieties. The jirobability of any extensive coal or 

 lignite deposit occurring in the formation will be afterwards 

 considered. The carbonaceous matter is found in the sand- 

 stone and conglomerate, or in the beds of clay. I have 

 specimens of it passing through every variety from a brown 

 lignite, with the scarcely altered characters of a dicotyle- 

 donous wood, to a scarcely bituminised coal, of rich black 

 with a high lustre and with no trace of woody structure. 

 In its most perfect state it is but slightly bituminised, and it 

 has mure the characters of jet than of coal. It is found 

 deposited in two ways ; first, in thin wavy laminse, from a 

 few Hues to a few inches deep, along the flexuous surface of 

 the thin beds of clay. It is likely that here it was formed of 

 vegetable matter left in small patches of limited lacustrine 

 basins, such as the small jhils of Hindostan, or in the bed of 

 a small sluggish stream. Secondly, in solitary masses, tra- 

 versing the sandstone strata, and forming the ends of a log. 

 It is often in such situations accompanied with a discolora- 

 tion of the sandstone about it, owing to impregnation with 

 iron from decomposed iron pyrites. It here has been formed 

 of the imbedded trunk of a tree deposited in the sandstone. 

 When of this description, it often retains a highly ligneous 

 character. Of a number of specimens which I have ex- 

 amined from different localities, the lignite has always been 

 of a dicotyledonous wood. I have seen no trace of any 

 monocotyledonous woody remains. I have not been able to 

 refer the woods to any class among the dicotyledones. No 

 specimen has shown any of the characters of the wood of 

 the Coniferse, although the fibres were examined under a 

 powerful microscoj)e. One very perfect specimen in my pos- 

 session, consisting of a large portion of the transverse 

 diameter of the trunk of a large tree, has the bark converted 

 into a substance nearly as hard and lustrous as jet ; the woody 



VOL. I. c 



