30 



Records of the Indian Museum. 



[Vol. VIII, 



A very interesting set of biological phenomena is illustrated 

 b}" the tadpoles of the Abor foot-hills, which agree precisely in 

 this respect with those of the Darjiling district and of hilly dis- 

 tricts in the Malay Peninsula. In the great majority of cases their 

 structure is adapted for life in rapid-running mountain streams 

 subject to sudden floods, and they are provided with special 

 apparatus with which to contend against the dangers incidental to 

 such a hfe. In other words, they possess special structural faci- 

 lities either for clinging to fixed objects or else for floating away 

 lightly on the surface of the flood. 



There has been considerable dispute as to the function of the 

 lozenge-shaped structure surrounding the mouth of the tadpole of 

 Mcgalophrys montana and similar species. Dr. Gadow suggests 

 that the peculiar teeth on the inner surface may be used for scrap- 

 ing the leaves of water-plants and Dr. van Kampen has observed the 

 tadpoles rasping algae from the sides of a glass aquarium with 

 them; but observations made in the Mala}^ Peninsula, Burma and 

 the Himalayas confirm me in the opinion, which was originally 



Fig. I. — Tadpoles of Megalophrys montana. 



advanced by Prof. Max Weber, that the chief function of the 

 whole structure is to act as a float whereby the tadpole can be 

 carried along on the surface, and also convince me that this 

 function is correlated with the fact that floods are one of the chief 

 dangers which tadpoles living in mountain streamlets have to fear. 

 I reproduce above a photograph of two living tadpoles of M. 

 montana taken some j^ears ago in the Malay Peninsula. One of these 

 tadpoles is lying at the bottom of the basin of water in which they 

 were photographed and has the float folded, the other has it ex- 

 panded on the surface. The water was too shallow for this tadpole's 

 tail to hang vertically downwards as it usually does. Dr. Gadow's 

 figure in the Cambridge Natural History is therefore more correct 

 in this respect. 



Although to act as a float is the main function of the oral 

 apparatus of these Megalophvys tadpoles, and although the teeth 

 on this apparatus are used for scraping off algae from stones (and, 

 I think from an examination of the contents of their stomachs, 

 also fungi from rotting wood), the apparatus has at least two other 

 uses. In the first place it facilitates breathing when the tadpole 



