OF CENTRAL INDIA AND BENGAL. 303 



fragmentary condition in which the remains of plants are so generally 

 found, but also from the marked similarity in form of the leaves of 

 widely distinct genera; the great variation in that form which frequently 

 occurs at different stages of growth, or in different parts of the same 

 plant; and from the doubt which must always exist in referring to the 

 same plant different parts (stem, branches, leaves, inflorescence) which 

 occur perhaps in immediate proximity in the same specimen, although 

 not actually joined together. 



Notwithstanding all these difficulties, inasmuch as these fossil plants 

 are, up to the present time (February 1860) the only organic evidence 

 which is known to exist in these rocks, we purpose, at present, briefly to 

 state the amount and character of this testimony, and by a careful in- 

 vestigation of its bearings, to see what light it is capable of throwing on 

 the disputed age of the rocks in question. Before entering on the fossil 

 evidence, however, we shall briefly state the successive steps which have 

 led to the establishment of the different systems, or groups, into which 

 we have found it necessary to divide the whole series of the bedded 

 rocks, as described in the preceding papers. 



In doing this we shall begin with the lowest group. It will be unne- 

 cessary to delay at present for any consideration of the highly metamor- 

 phic gneiss, hornblende, rock, crystalline limestone, &c, which cover 

 such an immense area in Bengal. It seems highly probable, indeed we 

 may say certain, that sub-division must be introduced among these rocks 

 also (as I have already stated elsewhere) (a). We shall, however, omit 

 any discussion of this point now, and pass to the other systems of beds. 



Sub-Kymore Group. — In the brief abstract of the labors of the Geolo- 

 gical Survey of India, which I submitted to the Asiatic Society of 

 Bengal early in 1856, I mentioned, (b) on the authority of Professor H. B. 

 Medlicott, the occurrence, resting immediately on the gneissose rocks of 



(a) Memoirs Geol. Surv. of India Vol. 1, p. 160, 



(b) Jour. Asiat. Soc. Bengal, 1856, p. 253. 



