120 Records of the Indian Museum. [Vol. XVI, 



in aquatic Prosobranchiate molluscs. It possesses both a gill and 

 a branchial chamber with a small orifice that can be completely- 

 closed. The branchial chamber, however, is not transformed into 

 a lung and is apparently never filled with air; breathing is effected 

 by the absorbtion of atmospheric oxygen through a thin film of 

 water. Cremnoconchus belongs to a family (the Littorinidae) of 

 which other forms are maritime, rupicolous or even arboricolous 

 and more or less amphibious. According to Pilseneer,' the bran- 

 chial cavity of some species of Littorina, though not transformed 

 into a lung like that of Pulmonates and though containing a gill, 

 is filled with air when the animals are out of the water, and with 

 water when they are submerged ; while other species of the same 

 genus '^menent ordinairement une veritable existence de Pnl- 

 mone." The physical modifications of the breathing apparatus 

 found in Cremnoconchus are not very greatly different from those 

 found in Littorina, but they are different and have a different 

 function. In the former genus the branchial cavitv is more of a 

 closed chamber; the structure of the gill,* though essentially 

 similar, is somewhat more simplified, its vascular outgrowths are 

 less developed and the osphradium is still more reduced, having 

 become papilliform instead of ridge-like. The small size of the 

 branchial orifice and the completeness with which it can be closed 

 are adaptations correlated with life in circumstances in which pro- 

 longed periods of desiccation occur. In these periods the animal 

 is in a state of coma and probably requires little fresh oxygen, but 

 the gill must be kept wet. 



Insects. — The insect fauna of damp rocks at Khandalla is a 

 rich one. In little ledges in which masses of damp algae grow 

 or dead leaves accumulate numerous dipterous larvae of the 

 families Tipulidae,^ Chironomidae and Stratiomyidae occur, with 

 small beetles belonging to the Staphylinidae, the Clavicornia and 

 other groups. In cracks in the rocks the earwig Forcipula 

 quadrispinosa and the Reduviid bug Pirates arcuaius are not un- 

 common, while Tettigine grasshoppers frequently alight on the 

 algae coating smooth surfaces. I shall, however, say nothing of 

 these, but merely draw attention to the great abundance of two 

 species of water-bugs, Hebrus bombayensis and Onychotrechus rhex- 

 enor. The former runs about on the damp alga and takes readily 

 to flight. It was also found on the surface of water at Medha, 

 and exhibits no particular modification for life on rocks. Onycho- 

 trechus is a genus which, so far as my experience goes, is always 

 found either on damp rocks or on the surface of small rocky 

 streams.* It differs from its nearest ally Gerris, which always 



1 Pelseneer, Arch, de Biol., XIV, p. 356 (1895). 



2 Stoliczka, Proc. As. Soc. Bengal, 1871, p. 108, fig. i. 



» An adult fly of this family found beneath a stone on a ledge in one of the 

 waterfalls has been identified by Mr. Brunetti as a new species of AnfocJia. 



* Mr. Green's remarks on O. vadda, Dist. (quoted by Distant on p. 147 of 

 Vol. V of the " Fauna " volumes on the Rhynchota) would apply equally well to 

 O. rhexenor at Khandalla. 



