K.— BOTANY. 207 



Measures are beds with marine fossils which Sir Edgeworth David states 

 indicate a Lower Permian or Upper Carboniferous age. These beds rest on 

 marine sediments rich in the shells of a Cejjhalopod, Paralegoceras Jacksoni, 

 remotely connected with the living Nautilus : this Cephalopod is inter- 

 preted by Dr. Dighton Thomas as evidence of an Upper Carboniferous 

 age. 



The evidence furnished by the Australian sections indicates the existence 

 of a flora, which in the northern hemisphere is accepted as Lower Carboni- 

 ferous, at a stage followed by strata which have furnished the oldest 

 members of the Glossopteris Flora. The break in succession at this level, 

 between the Kuttung and Lower Marine series, is regarded by Schuchert 

 not merely as evidence of shifting of the scenes inaugurating a new type 

 of vegetation — the Glossopteris Flora,^ — -but as representing a long interval of 

 time during which rocks of Upper Carboniferous age were being deposited 

 in the northern hemisphere. It is difficult to believe that events which 

 occurred during the latter half of the Carboniferous period are entirely 

 lacking in the geological records not only of Australia, but of India and 

 South Africa. The more probable view, in my opinion, is that the Lower 

 Marine Series and the corresponding strata in Western Australia containing 

 Paralegoceras are homotaxial with the Upper Carboniferous system in 

 Europe and North America. 



There has been much discussion on evidence relevant to the age of the 

 Glacial period and the Glossopteris Flora, derived from the Indian Peninsula 

 and from regions farther north. In the Salt Range a boulder bed, believed 

 to be the equivalent of the Talchir tillite of the Peninsula, is overlain by 

 rocks containing marine fossils including Eurydesma, which, as stated 

 later, favours an Upper Carboniferous age. Resting on these beds — the 

 Speckled Sandstone- — is the Productus limestone with Permian marine 

 fossils. In Kashmir Gatigajnopteris was discovered low down in a thick 

 series of beds overlain by strata known as the Zewan series, the lower 

 portion of which is probably Lower Permian, if not Upper Carboniferous 

 in age. Prof. Schuchert, after mentioning the discovery of Gangamopteris 

 and Glossopteris ' in marine strata beneath fossils of the Productus lime- 

 stone,' goes on to say that this discovery proves that the Gangamopteris 

 Flora is of Upper Permian time.' 



The age of the Productus Limestone is a determining factor in Prof. 

 Schuchert's contention, and as the evidence is outside my own province I 

 consulted Dr. Dighton Thomas, of the British Museum, who has made a 

 special study of the palaeozoological data bearing on the correlation and 

 age of the Carboniferous and Permian rocks with particular reference to 

 the problems under dispute. Dr. Thomas points out that ' the question 

 of the lower limit in age of the Productus Limestone series, and of the 

 beds below them as far as the boulder bed, hinges on the means of deter- 

 mining the age of the Amb to Virgal series [of the Salt Range].' In his 

 letter of April 19, from which he kindly allows me to quote, he goes on to 

 say that the best means of settling the age of the Salt Range beds is 



^ For a full discussion of the evidence bearing on the geological age of strata in 

 the Salt Range in Kashmir and other districts, reference should be made to two 

 Presidential Addresses delivered respectively by Prof. Sahni and Prof. Das-Gupta at 

 the Eighth and the Fifteenth Indian Science Congresses. 



