530 Records of the Indian Museum. [Vol. XXII , 



INTRODUCTION. 

 By N. Annandale. 



Among the districts on the frontiers of Burma few have 

 greater interest for the zoologist than Manipur. the position of 

 which is thus defined by Mr. B. C. Allen in the official Gazetteer 

 of the Naga Hills and Manipur ( Calcutta : 1905 ). 



"The Native State of Manipur is situated between 28° 50' and 

 25° 41' N. and 93° 2' and 94° 47' E. and covers an area of 87,456 

 square miles. On the north it is bounded by the British district 

 of the Naga Hills, on the west by Cachar, on the south by the 

 Lushai Hills and Burma, and on the east by Burma." 



The greater part of the State is occupied by mountainous coun- 

 trv, which, though of great zoological interest, is less important from 

 the point of view of the study of the freshwater molluscs than the 

 comparatively small valley that forms the richer and more civilized 

 part. I propose, therefore, to say no more than a few words 

 about the hill-streams and their fauna and to devote the greater 

 part of this introduction to a succinct account of the valley. 



Within the limits of the State of Manipur small hill-.streams 

 that belong to several different water-sheds 

 Hill-streams of Mani- occur, viz. (i) those that flow down into the 

 ^"'^^ valley- ; (2) those that flow northwards to 



join the Brahmaputra system ; (3) those that flow eastwards to 

 Burma and (4) those that flow westwards towards Sylhet. The 

 fact that the hill-tracts of the state are much more extensive 

 thouoh less valuable than the valley renders the number and direc- 

 tion of their streams large and varied. Hill-streams, however, 

 rarely have a rich molluscan fauna and the only ones in which my 

 party was able to make collections were those that entered the 

 valle'v and those that flowed northwards to the other side of the 

 Naga Hills. 



The streams closely resemble those of other hill-ranges in 

 north-eastern India. They are as a rule little more than mountain 

 torrents, though in some of the valleys among the hills they may 

 assume for a time a placid and even course. Their beds are for 

 the most part rocky or stony and there is little aquatic vegetation. 



The fauna of such streams has a very similar facies all over 

 south-eastern Asia from Nepal to HongKong 

 Fiuna of Oriental Hill- ^^^ probablv to Formosa and the Philip- 

 streams, pines. Its main characteristics are : (i) the 

 production of special adhesive apparatus, more particularly in the 

 Batrachian larvae, fish and insects, all of which provide numerous 

 and highly interesting instances of convergence in this respect, and 



