i 9 i6.] 



Fauna of the Chilka Lake : Mollusca Gastropoda, etc. 



331 



Gastropoda. 



Nassidae. 



Bullia vittata, Linn. 



Strombidae. 



Strombus Isabella, Lk. 



Viviparidae. 



Vivipara bengalensis , Lk. 



Ampullariidae. 



Ampullar ia globosa, Swains. 



Naticidae. 



Natica marochiensis , Gmel. 

 ,, maculosa, Lam. • 



LAMELLIBR ANCHIATA . 



Veneridae. 



Meretrix morphina, Lk. 

 Meröe scripta, Gray. 



„ chilkaënsis , Preston. 



,, satparaënsis, Preston. 



Donacidae. 



Donax pulchella, Hanley. 



Tellinidae. 



Tellina barhampurensis, Preston. 



Dead shells of the freshwater Gastropods that live in pools and rice -fields are 

 common on the shores of the lake and are occasionally carried into it by winds, by 

 birds and by hermit-crabs of the semi-terrestrial genus Coenobita, which also bring 

 marine shells, such as those of Natica and Strombus, across the sand-hills from the sea. 

 Marine shells, especially those of Lamellibranchs, are commonly collected on the sea- 

 shore by Uriya fishermen and used for the manufacture of lime, lime from this source 

 being highly esteemed as an ingredient in pan. Such shells are often dropped in 

 the neighbourhood of villages. They must be carefully distinguished from the sub- 

 fossil shells found at certain places (see p. 338). 



The living Mollusca of the lake, omitting Nudibranchs and introduced shells, are 

 listed on pp. 332, 333 and 1 comprise, so far as our knowledge goes, 73 species, 31 of 

 Gastropods and 42 of Lamellibranchs. The Gastropods are distributed among 14 

 families and 19 genera, the Lamellibranchs among 20 families and 25 genera. No less 

 than 28 species, with one genus (Chilkaïa) — that is to say, about 38 % of the total 

 number — appear at present to be endemic in the lake-system. 



The great majority of the genera are certainly of marine origin, the only excep- 

 tions being Potamides, Chilkaïa (?) , Hydrobia and Stenothyra. Potamides is essentially 

 an estuarine genus and the two species by which it is represented occur commonly in 

 brackish water all over the Oriental region, in Australia and in Japan. The genus 

 Chilkaïa, as at present known, is represented by a single minute species belonging 

 to a family the other members of which are marine. On the other hand Hydrobia and 

 Stenothyra belong to a family of which most of the species inhabit fresh water, but 

 many make their way into estuarine tracts and are found only in brackish water. 

 This is the case with most of the Indian species. More than half of those of Stenothyra 

 known from India have been found in the Chilka Lake. 



1 The figures in the second column of this table indicate the specific gravity of the water in which 

 living specimens were obtained. Species which, so far as is yet known, are endemic in the lake-system 

 are distinguished by an asterisk. 



