Chap. I.] historical summary. 15 



description of the country surveyed. The Palseontological and Geog- 

 nostic questions, which are solved by the study of these organic remains, 

 may however be easily kept distinct, and we may regard the fossils either 

 as mere indices for the identification of rocks not visibly continuous, in 

 which point of view a Geological Surveyor has chiefly to deal with them, 

 or we may study them in their Biologic aspect as indicating the 

 conditions of a deposit and affording evidence of the distribution, 

 succession, and other relations of beings in past time, — questions 

 which pertain to the province of the Naturalist and the Theoretical 

 Geologist. In the following pages, I have therefore refrained from 

 entering into Paleeontological questions, except in one case, beyond 

 the mere enumeration of such well identified genera or species as have 

 been met with in different localities, reserving all else for a future 

 publication. The exception I refer to, is the question of relative age 

 of the Pondicherry beds as compared with those of Trichinopoly. In 

 this case, in the absence of any sufficient stratigraphic evidence, we 

 are compelled to fall back on that of the fossils ; but the task is here 

 rendered easy' by the circumstance, that the fauna of the former beds 

 has been already weU. investigated by one of the first Palaeontologists 

 of modern times, whose conclusions, as regard these beds, have received 

 unexpected confirmation in the clearing up of those discrepancies 

 which he and others noticed, and which led Sir P. Egerton, and in 

 part also, M. D'Orbigny, to doubt the accuracy of his conclusions. 



