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SOME TERRESTRIAL ISOPODA FROM THE SHORE OF 



THE LAKE. 



By Chas. Chii/ton. 



INTRODUCTION. 



Among the Isopoda and Amphipoda collected during the Chilka Lake Survey, 

 and kindly handed over to me by Dr. Annandale for examination and report, there 

 are four species of Terrestrial Isopoda collected on the shores of the lake. As these 

 are the only representatives of the Oniscoidea l in the collection sent to me, and as 

 they differ from the other Isopoda in being terrestrial, it will be convenient to deal 

 with them in a separate report. 



Naturally the number of species is small, since the Survey dealt with the lake 

 itself, and only those terrestrial forms found near the shore were collected. Of the four 

 species Ligia exotica is the only one that can be looked upon as strictly belonging to 

 the Lake Chilka Fauna. It is a maritime species never found far from the sea- shore. 

 Specimens were obtained during the Survey from two localities near Barkul and from 

 Barkuda Island, 1 where the water is somewhat brackish even during the season when 

 the main area of the lake is filled with fresh water. Most species of Ligia live near 

 enough to the sea-shore to be affected by high tides or by the salt spray, but in some 

 cases, where conditions are favourable, they have been found in moist places at some 

 considerable distance from high tide mark. As the margin of Lake Chilka varies 

 considerably during the different seasons and as the salinity of the soil at the south- 

 ern end is greater than that nearer the mouth of the Mahanaddi, it would probably 

 afford a good opportunity of showing how a maritime species, such asL. exotica, may 

 become gradually adapted to more purely terrestrial conditions, but the specimens 

 at present in my hands do not throw any light on this question. 



Ligia exotica is a widely distributed species, found on the sea- shore of many 

 parts of the Indian, Atlantic and Pacific Oceans. 



The other three species appear to be purely terrestrial forms. The type speci- 

 mens of Hemiporcellio carinatus, previously described by Mr. Collinge (1915, P- i 45)j 

 were collected "under stones and dead water weeds at the edge of Chilka Lake" 

 at Rambha, and speaking of it Dr. Annandale says, "apparently an amphibious 



1 Arhina barkulensis, Collinge (Rec. Ind. Mus., XI, p. 147, pi. viii) was also taken at the edge of the 

 Chilka Lake. 



" 2 For the position of these places and for information on the geography, hydrography, etc., see the 

 " Introduction " to the •' Fauna of the Chilka L,ake " by N. Annandale and S. Kemp (1915, pp. 1-20). 



