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



perhaps the most abundant of all is the Watei'-chestnut (Trapa 

 hispinosaY , which has leaves floating on the surface as well as a 

 profuse growth under water. The floating leaves dot the whole 

 surface of the more open parts of the swamp, growing up through 

 dense thickets of Potamogeton and Hydrilla. The leaves and stems 

 of these completely submerged plants are as a rule densely covered 

 with small algae, and it is quite exceptional to find beds of any 

 kind of water-weed that have a clean appearance. 



In the channels among the floating islands surface-plants such 

 as Pistia, Azolla and Leinna are often fairly abundant, but not 

 sufficiently so to play a great part in the formation of the islands. 



These islands are not so coherent and do not support so varied 

 and luxuriant a flora as do those of the Inle Lake. The chief agent 

 in their formation is a comparativelj' small grass which sends out 

 long trailers on the surface of the water. A Caladiuin, several 

 species of Polygonum and a fern are common upon them, but the 

 bulk of the vegetation consists of grasses and sedges. 



The islands are not used for horticulture or stock-keeping as 

 are those on the Inle Lake, but occasionally small fishing huts 

 are built on the firmer islands, and pieces are frequently cut off 

 from, them and towed away to be utilized in forming fishing- 

 enclosures. 



A whole volume of these Records was devoted to the fauna of 



the Inle Lake and the help of a number of 



.SnilVoUKTlli:! speci^^lists was invoked in its preparation. 



Lake. It is unnecessary to aeal with the fauna of the 



Loktak Lake in the same detail, because it is a 



much less isolated association and does not consist for the most 



part of highly specialized species of animals. It will, therefore, be 



sufficient to have the molluscs and the fish completely worked 



out and to mention here a few salient representatives of other 



groups. The molluscs will be described in full in the succeeding 



paper, and has already Mr. Sunder Lai Hora dealt in detail with 



the fish. Here I shall merely refer to these groups as constituting 



the most important elements in the fauna and give a few facts of 



a general kind about them. 



Conditions in the Loktak Lake are favourable to the growth 

 and reproduction of Protozoa and many water-plants were observed 

 that bore a profuse growth of Vorticellids. Small masses of sponge 

 were found in considerable abundance on the weeds of the open 

 parts of the lake. On examination they proved to belong to but 

 one species, Spongilla carteri, the commonest and most generally 

 distributed of the Indian Spongilhdae. They differed, however, 

 from the typical form of the species in the small size and irregular 

 shape of individual sponges. No Hj'drozoa were observed and the 

 only polyzoon collected was immature — evidently a species of 



1 This plant is utilized as a vegetable in large quantities by the people of .Mani 

 pur, who unlike most Indian races, employ the leaves as well as the roots as an 

 article of food. 



