1915.] Fauna of the Chilka Lake : Crustacea Decapoda. 249 



In very young specimens the carapace is proportionately much longer than in 

 adults and the frontal margin is entire and not cut into teeth. 



The range of the species in the Indo-pacific region is closely similar to that of 

 Scylla sen ata. 



Genus THALAMITA, Latreille. 



Thalamita crenata, Latreille. 



1899. Thalamita crenata, Alcock, Journ. Asiat. Soc. Bengal, LXVIII, p. 76. 



This species is not uncommon on the oyster-beds at Manikpatna in the outer 

 channel of the Chilka Lake and was found both when the water was fresh and when 

 it was salt. It does not, in our experience, occur in the main area of the lake. 



The distribution of T. crenata is co-extensive with that of the two preceding 

 species. 



Tribe PAGURIDEA. 



We are indebted to Dr. J. R. Henderson, Superintendent of the Madras Museum, 

 for an account of the hermit-crabs of the Chilka Lake. 1 



The species identified by Dr. Henderson are seven in number. One of these is a 

 form hitherto unknown, which is described under the name of Clibanarius olivaceus, 

 and another, Diogenes miles (Herbst) , is represented by a single individual obtained 

 on the sea-shore near Rambha. The latter species is not a member of the lake fauna 

 proper; it may perhaps wander at times to the shores of the outer channel, though 

 we never found it there. 



It is noteworthy that most of the Paguridea found in the lake are represented 

 only by very small specimens. This is possibly due to the fact that their environ- 

 ment, with its great seasonal changes in salinity, hinders a more complete develop- 

 ment ; but it seems more probable that it is caused by the absence of any shells large 

 enough to accommodate full-grown specimens. Except for a few Telescopium fuscum, 

 found in the outer channel and frequently inhabited by moderate-sized Clibanarius 

 padavensis , the largest gastropod both in this part of the lake and in the main area 

 is Thais (=Purpura) carinifera, a shell much too small to accommodate large indivi- 

 duals of any species except Diogenes avarus. In the main area the distribution of 

 Thais is restricted and coincides with that of Clibanarius. 



Family PAGURIDAB. 



Genus CLIBANARIUS, Dana. 



The three species of this genus found in the Chilka Lake are very closely allied 

 to one another ; but, as Henderson has pointed out, are readily distinguished by their 

 colouration. C. padavensis and C. longitarsis are very widely distributed forms, and 

 all three are essentially inhabitants of brackish water. 



1 Henderson, Rec. Ind. Mus., XI, p. 25 (1915)- 



