R. D. Oldham — On Homotaxis and Contemporaneity . 299 



ably on the older Palaeozoics. This would imply a greater difference 

 of age than seems to obtain between the Hawkesbury and overlying 

 groups in New South Wales. To this I may add the difference in 

 induration of the two, which is such that when originally surveyed, 

 the Bacchus Marsh beds were believed to be Devonian, and are 

 coloured on the original survey sheets as Upper Palaeozoic. 



As a further confirmation of the opinion ventured on, I may point 

 to the relationship that exists between the flora of the Damudas 

 which overlie the Talchir group in India, and that of the Newcastle 

 beds, which occupy a similar position above the Lower Carboniferous 

 marine group in Australia. 



To begin with, both floras are marked by the predominance of the 

 genus Glossopteris, which, in the Newcastle flora, comprises nine out 

 of 26 species, or 35 per cent, of the total number of species, and 19 

 species out of 63, or 30 per cent, of the total number of species in 

 the Damuda flora ; of these, one species, G. broioniana, is identical 

 in both cases, and three Newcastle species, G. linearis, G. ampla, and 

 G. parallela, are represented by the allied Damuda species, G. 

 angustifolia, G. communis, and G. damudica. The genus Phyllotheca 

 is represented in both floras, and the Australian form is allied to, 

 and was long considered identical with, the P. indica of the Damudas. 

 Vertebraria is found in both series, and is only known elsewhere 

 from the "Jurassic" beds of Siberia. Sphenopteris alata, Brong., is 

 another species represented by allied forms in the Damuda flora, and 

 Gangamopteris angustifolia, M'Coy, is common to the two floras. 

 Besides these the genus Noeggerathiopsis is represented in both floras, 

 so that we have in all six genera and two species common to the 

 two floras, besides five species represented by allied forms. In other 

 words two-thirds of the genera and more than a quarter of the species 

 of the Newcastle flora are represented in that ot the Damudas. 



Taking all these points into consideration, I think we may safely 

 affirm that the Talchirs of India, the Ecca beds of South Africa, the 

 Bacchus Marsh beds in Victoria, and the Marine beds below the New- 

 castle Coal-measures in New South Wales, were all deposited con- 

 temporaneously, and that during their deposition there prevailed 

 a Glacial epoch comparable to, if not even more severe than, that of 

 the Pleistocene period. 



This conclusion brings out the contradictory nature of the Palaeon- 

 tological evidence even more strongly than it was possible for Dr. 

 Blanford to do in his address, for it shows that the coexistence of 

 a Jurassic flora with a Carboniferous fauna was no mere local phe- 

 nomenon, but that the Jurassic flora had established itself over nearly 

 half a hemisphere, while the Carboniferous Mollusca were still 

 inhabiting the seas. 



In the face of this contradiction, it may be allowable to doubt 

 whether either form of palaBontological evidence can be regarded as 

 absolutely trustworthy, and to question whether the beds containing 

 the Lower Carboniferous marine fauna may not have been deposited 

 synchronously with the deposition of the Permian Boulder-beds of 

 England, and with certain Boulder-beds which are known to exist 



