PEESIDENl S ADDEESS. 



257 



to show there is something more than an indication that Girasia is 

 the more recent development, and the same line of reasoning points 

 to Macrochlamys being relatively in turn the more primitive genus. 

 It is not so easy to locate Oxytes and Jienso?iia ; the probability is 

 that they started like Macrochlamys from some no longer existing 

 form, and have had a cotemporaneous development with Macrochlamys 

 itself. 



The following diagram is a graphic representation of the possible 

 succession of a few of these genera: — 



( Section C. rubra. Naga Hills. 

 Girasia \ „ B. Hookeri. Khasi Hills. 



( ,, A. jDiissumieri. South India. 



A.ustenia gigas. Khasi Hills. 



3Iacrochla7nys. 

 Section A. Indica. Bengal. 



,, B. atricolor ^North Burma & 

 ,, C. Caeharica ) Naga Hills. 

 ,, D. pedina. Bombay. 

 ,, E. resplendens. Tenasserim. 



Bensonia lahiata. N.W. Himalaya. 

 Oxytes oxytes. Khasi. 



Xesta eitrina. Malayana. 



Hemiplecta Humphrey siana. 

 / Singapur. 



When one examines the genera from South India and Ceylon, one 

 cannot but fail to be impressed with the many important points in their 

 anatomy, which differentiate them from genera of the same family 

 occupying other parts of India. "Without enumerating the many 

 genera and species of other families which are quite peculiar and 

 restricted to this Peninsula, the number of genera 1 have brought to 

 your notice in this address is large and characteristic of isolation. 

 Nor is this more than might be expected, as the result of the past 

 conditions over a considerable part of this area. The geological 

 evidence indicates that this part of India is one of the oldest of land 

 surfaces on the globe. Ever since the east and west Cretaceous 

 oceans washed its shores, the fringing line of which is preserved at 

 different points, some part of it at least remained dry land. Yery 

 similar conditions appear to have existed during Nummulitic times, 

 and not until the advent of the Eocene does there appear to have been, 

 any connection with Palsearctic lands and fauna on the north-west. 

 With the deposition of the Nahan series of deposits in a gradually 

 sinking belt, under conditions which, there is every reason for supposing, 

 were alluvial, not far from and just keeping above the sea-level, 

 a broad dry land connection was established. We may imagine 

 the great alluvial plain of Maimensing and Sylhet, between the line 

 of mountains and the sea, to be representative of such conditions 

 there; for there may be seen the piling up of similar deposits of 



VOL. III. — JULY, 1899. 



18 



