iç)i5'] Fauna of the Chilka Lake : Introduction. 19 



Protozoa and Rotatoria. The smaller Entomostraca were collected merely as they 

 occurred in tow-nettings. In the majority of groups larval forms, with a few specific 

 exceptions, were also neglected, while certain other small and inconspicuous organisms 

 {e.g., the free-living Nematodes) were obtained only in small numbers. 



We regret that we were unable to study the ornithology of the lake, which is 

 remarkably attractive at different seasons to different kinds of water-birds, though 

 comparatively few breed there habitually. 



In a few groups of animals of which we did make fairly comprehensive collec- 

 tions, it has not been possible in the present state of international affairs to find 

 specialists able and willing to investigate the specimens. The most noteworthy of 

 these groups are the Nemertea and the aquatic beetles. Of the former at least three 

 species are common in the main area of the lake, while both the Dytiscidae and the 

 Hydrophilidae are represented by a considerable, but not a large, number of forms. 

 We failed to get the two species of Nudibranch molluscs that occur identified, while 

 the single Tunicate we obtained (an immature Appendicularian common in the 

 outer channel in March) is probably not determinable specifically. 



Among internal parasitic species we preserved a certain number of Helminthes, 

 especially Cestoda from the alimentär}' canal of sting-rays. Mr. T. Southwell has also 

 collected specimens of this group in the lake and is preparing a report upon his and our 

 collections. 1 The parasitic Nematodes are poorly represented and there is only one 

 Acanthocephelon, which was found in the intestine of a Teleostean fish. The Trema- 

 todes are represented by at least three species, a large and common form from the 

 body-cavity of a ray and two minute Distomids, one occurring in the canals of a 

 Ctenophore and the other in the body-cavity of a Copepod. We do not propose to 

 discuss these internal parasites further except in reference to their hosts. 



Of the groups that appear to be actually absent from both the outer channel and 

 the main area, the most conspicuous are the Echinoderms and the Cephalopod ' l mol- 

 luscs. Certain other divisions of the latter phylum, e.g., the Pteropoda, seem also to 

 be unrepresented in the fauna, as is the case with several groups of coelenterates, 

 notably the Cubomedusae and the stony corals. The aquatic insects are naturally 

 represented by but a few of those families which possess aquatic larvae. 



Apart from such limitations, there are also others dependent on mechanical diffi- 

 culties in collecting. Our collections from the main area of the lake, considering the 

 multitude of individuals and the paucity of forms, are probably almost complete ; a 

 few rare species may have escaped our notice, but it is doubtful whether this is the 

 case with the common animals, which are, of course, very much more important from 

 a faunistic point of view. If any of the latter are missing it is probably among the 

 fish that gaps occur. In the fauna of the outer channel on the other hand there 

 are probably many gaps both in the vertebrates and in the invertebrates. All 



1 Rec. Ind. Mus., ined. 



2 Goodrich (Trans. Linn. Soc, Zool. (2) VII, pp. 5, 7, 1896) records specimens of Sepiella inermis 

 (van Hasselt) and Loligo indica, Pfeffer, from the " Chilka Bight ", but they were probably obtained 

 outside the mouth of the lake, as they are from the ' Investigator ' collections. 



