328 GEOLOGICAL RELATIONS OP THE ROCK SYSTEMS 



see nothing to justify the idea that we have the leaves of a plant in 

 any of. its forms ; and I am disposed to think that Vertebraria will 

 prove to be a root, with smaller rootlets attached. Certain it is, that 

 these puzzling fossils are found under circumstances which indicate that 

 their vegetable matter contributed very largely to the formation of the 

 coal of this country ; and to a great extent they play the same part 

 in the Indian Coal-field that Stigmaria does in English fields. fa) 



Of Phyllotheca we have at least one, probably several. Of Pecopteris, 

 our specimens shew I think, that P. Lindleyana of Royle is identical 

 with P. Australis of Morris. Of Sphenopteris, one species is certainly 

 common to Australia ; one approaches very nearly to S. bifida of the 

 Scotch Coal measures. 



There remain then the remarkably numerous and largely varied forms 

 of Glossopteris. This in fact from its great abundance and from the great 

 size of many of the leaves, is the most characteristic fossil of the group. 

 And it may be necessary to say a few wordsj'egarding this genus of ferns. 



In the Indian Coal-fields we have all the varieties known from Aus- 

 tralia, and all the typical varieties described by Brongniart, together 

 with several others not hitherto figured. I cannot trace the grounds 

 on which it has been so frequently and positively repeated that Glossop- 

 teris is a " truly characteristic oolitic genus." This assertion has been 

 reiterated so constantly, as to have formed the basis of much reasoning 

 on the age of the rocks in which Glossopteris leaves have been found. 

 It is one of the strongest arguments given by Mr. McCoy in his sum- 

 mary of the evidence from the Australian plants.(6) It is equally one 

 of the strong points urged by Mr. Hislop in his discussion of the age 

 of the Indian coal-strata. It is by others called a " distinctive oolitic 

 genus*" " a genus of oolitic ferns." &c. 



(a) See Logan's valuable paper. On the character of the beds of clay below the Coal 

 seams of South Wales, &c. Transac. Geol. Sur. London, Vol., VI. 2nd Series, p. 491. 



(b) Annals of Natural History, London, 1847, p 310. Vol. XX, 1st series. 



* Miller Testimony of Rocks p. 483, &c. 



