1844.] Construction of a Chapter in the History of the Earth. 189 



can doubt, that the Indian and Australian forms of the celebrated 

 Glossopteris hrowniana, long believed to belong to the same species, 

 differ so widely in their fructification that it is doubtful whether they 

 can be included in the same family, and that they must certainly belong 

 to different genera.* 



As an instance of uncertainty of palaeontological evidence, I need only 

 quote the well-known case of the Umia and Katrol beds of Kutch, where 

 beds containing a flora with a well-marked Lower Oolite facies overlie 

 other beds in which the fauna is equally distinctly Upper Oolite in type ; 

 another case that might be quoted is that of the Rajmahal and Damuda 

 floras ; in the Rajmahal flora, there are, out of 47 speciesf in all, 26 which 

 are identical with or allied toj European species : of these, fifteen are 

 represented in the Rhaetic beds of Europe, one species being hardly 

 distinguishable from the European form : seven are represented by 

 PaloBozoic species, two belonging to an exclusively Palaeozoic genus 

 (Ercmopteris) ^ while another (Macrotoeniopteris lata) is, on Dr. Feistman- 

 tel's own admission, so like the Permian Tamiopteris ahnormis as to be 

 almost undistinguishable : two species only are allied to Liassic forms, 

 and of these one is also represented in the Rhaetic : five species are re- 

 presented in the Lower Oolite of Europe, two by identical forms, while, of 

 the other three, one is also related to a Carboniferous, and the other 

 two to Rhaetic, species. From this, an impartial observer would be in- 

 clined to place the flora as certainly not later than Rhaetic, but, as on this 

 point the talented palaeontologist of the Geological Survey has expressed 

 a very positive opinion that the flora is Liassic in facies, I must perforce 



* Palseontologia Indica, Fossil Flora of the Lower Gondwanas, Vol. Ill, p. 103 

 In this connection, I may quote Dr. Feistmantel as follows : — after noting the difference 

 in the fructification of the two forms, he adds ' so that I would be quite justified in 

 placing these in a separate genus altogether and thus disposing of the difficulty in 

 determining the age of our Damuda series owing to the correlation of the Indian 

 Australian species." An easy way of ' disposing of the difficulty ' forsooth, but my 

 colleague can hardly have perceived the full force of those words when he penned 

 them, for, carried to their legitimate conclusion, they cut away the ground on which 

 alone palseobotanists can base their claim for the acceptance of fossil plants as a 

 means of correlating distant deposits. The lesson to be learnt is rather that the 

 conclusions of even the ablest palajobotanists must, owing to the nature of the 

 material they have to work with, be received with caution, and that generic and spocifio 

 names of fossil plants do not necessarily represent any real affinity, and that in some 

 cases the latter and in most cases the former are names merely and nothing more. 



t Here and elsewhere, except where the reverse is distinctly stated, I owe ray 

 palseontological facts to Dr. 0. Feistmantol's writings in the publications of the 

 Geological Survey of India. 



X I use this term in the same sense as it is used by palseobotanists ; it may 

 well be that some of these ' allied apuciea ' have no j-ual coiaieuLioii with each other. 



