P1ANT-BEAKING SERIES OE INDIA. 525 



thickness of the Jurassic series is estimated at 6300 feet, of which 

 8000 feet belongs to the upper group. 



The facts above given suffice to establish approximately the age 

 of the Cutch representatives of the highest members of the plant- 

 bearing series, as being probably not older than the youngest 

 member of the Jurassic formation — the Tithonian. The evidence 

 of the Trichinopoly plant-beds, as far as it goes, is corroborative ; 

 and it may be mentioned that the lower members of the Cretaceous 

 series themselves, though not containing leaf-remains, abound in 

 fragments of wood, which Dr. Thomson recognized as Cycadaceous*. 

 The stratigraphical relations of the Trichinopoly and Cutch plant- 

 beds, apart from the palseobotanical evidence of their contents, 

 indicate that they belong to about the same geological horizon, 

 even if not absolutely equivalent ; and on this point we may expect 

 further evidence when the associated marine fossils shall have been 

 fully worked out. Meanwhile they may be regarded as probably 

 Tithonian, possibly of Wealden age. This being determined, the 

 identity of some of the characteristic plants in these and the 

 Jabalpur and Rajmahal rocks of Central India and Bengal 

 justifies the inference that these latter are also approximately of 

 similar age ; and, indeed, the former cannot be much newer, since 

 they are overlain unconformably by the Lameta group, with which 

 Mr. W. T. Blanford identifies f the fossiliferous limestones of Bagh, 

 which contain marine fossils of a Lower Cretaceous type J. Some 

 bones, apparently Reptilian, have been found in these Lameta-beds 

 near Jabalpur, but too imperfect for determination §. 



The age of the lower groups is a much more difficult question. 

 The general opinion, deduced chiefly from the fossils sent home by 

 the late Mr. Hislop (from the Kamthi and Panchet rocks), appears 

 to be that they belong to the lower part of the Mesozoic series ; but, 

 as Dr. Oldham has remarked, this opinion appears to have been in- 

 fluenced very much by the supposed Oolitic affinities of the genus 

 Olossopteris. This view was combated by Dr. Oldham in the 2nd 

 volume of the ''Memoirs of the Geological Survey '|!> when he 

 showed that the plants from the European Oolites referred to that 

 genus have no claim to be so considered, and consequently that any 

 inference of the Jurassic age of the Coal-bearing rocks of Bengal 

 based on such supposed affinities is invalid. Sir Charles Bunbury 

 mentions^ one Phylloiheca as occurring in the Oolitic rocks of Italy, 

 on the authority of Baron de Zigno; but while inclining to the 

 opinion that the Kamthi rocks are Mesozoic, he insists but little on 

 the evidence of the plant-remains, and concludes that, " such as it 

 is, it might be outweighed by the discovery of a single well-marked 

 and characteristic fish, shell, or coral." 



In considering the question of age we must be careful to bear in 



* Mem. G. S. I. vol. iv. art. 1. p. 49. 



t Mem. G. S. I. vol. vi. art. 4, p. 56, and vol. ix. art. 2, p. 36. 

 | Duncan, Quart. Journ. Geol. Soc. vol. xxi. p. 349. 

 ~ Mem. G. S. I. vol. ii. p. 199. |[ See p. 328. 



Quart. Journ. Geol. Soc. vol. xvii. p. 344. 



