1 8 Memoirs of the Indian Museum. [Vol. V, 



in waters of different salinities at temperatures ranging from io° to 35°C. We are 

 under great obligation to Dr. W. A. K. Christie, Chemist to the Geological Survey of 

 India, for advice and practical assistance in this matter. 



The positions of our stations in the lake were determined by the use of a sound- 

 ing quintant and station-pointer kindly lent us by the Survey of India. 



The specimens on which the reports in this volume are based are at present in 



the Indian Museum, in which all the types of new 

 Collections. . 



species described, as well as a complete set of all 



other forms, will be preserved. The oldest specimens from the Chilka Lake that 

 we possess are a few shells collected by the late Dr. W. T. Elanford and his agents, 

 mostly, as is evident from the species represented, in the outer channel. The 

 Museum collector obtained a considerable number of fish in the neighbourhood 

 of Gopkuda Id. in 1907, while Dr. J. Travis Jenkins made collections, also 

 mainly of fish, in the outer channel in 1908. One of the present authors paid a 

 short visit to Rambha in the following year and obtained there, among other 

 material, the types of several new shells described by Mr. H. B. Preston. It was 

 not, however, until August, 191 3, that any concerted attempt was made to investi- 

 gate the bottom-fauna. In that year wa used bottom-nets for the first time in the 

 lake, mainly in the immediate neighbourhood of Barkul. In October of the same 

 year we commenced preliminary work at Satpara and Rambha, and subsidiary trips 

 were made in November and in the following January. Our actual survey com- 

 menced in February, 1914. Apart from a number of short visits to one or other 

 region of the lake, it was conducted, as has already been stated, mainly at two 

 periods, representing respectively the middle of the salt-water and that of the 

 fresh- water season. In February and March we spent altogether about six weeks on 

 the lake, on which we trawled practically every day, while in September a period of 

 about three weeks was occupied in the same manner. Our own shorter trips were 

 made in April, July, November and the beginning of December, while Dr. B. I,. 

 Chaudhuri collected fish at Barkul and elsewhere in December of the same year and 

 in January, 1915 



We have in our log particulars of 171 collecting stations. In some cases the 

 data of two or more stations refer to the same place at different seasons, but many 

 specimens were collected, on the subsidiary trips and at other times, in circumstances 

 not noted in the log, though recorded on the labels. 



The bulk of the collections is of course very considerable and it will therefore be 

 possible for us to distribute to other museums by the only means open to us (i.e., 

 that of exchange) a number of sets of duplicates. 



"Limitations of the Work. 



Neither the time nor the funds at our disposal were unlimited and even within 

 the somewhat narrow boundaries to which the survey was confined, we were obliged 

 to observe certain limitations in collecting. Generally speaking we made no special 

 effort to capture and preserve representatives of microscopic groups such as the 



