68 ON THE ORISSA COAST 



almost have been passed aside as part of the shell of 

 a dead bivalve ; a mole-crab i^Hippa asiatica) of gre- 

 garious, burrowing habits, whose development I was 

 able to trace satisfactorily ; and a bat-lobster ( Themis 

 orientalis), whose newly-hatched larvae I was able to 

 preserve. 



We also made a fine collection of the fishes that 

 swarm in such incredible numbers in the estuaries 

 and shoal waters of the Orissa coast. Here, too, we 

 found much that was worthy of observation, such, for 

 example, as the fishes which croak like frogs. It has 

 been known from the time of Aristotle, that many 

 fishes are able to utter sounds which are more or less 

 musical and purposive, and are quite distinct from the 

 meaningless gaspings and gurglings of a fish taken 

 out of water, and many writers have sought to 

 explain the mechanisms by which these sounds are 

 produced. In some cases they are supposed to be 

 caused by grinding together the bones of the pharynx, 

 or by snapping fin-spines in their sockets ; in other 

 cases they may, perhaps, be due to rhythmical con- 

 tractions of the air-bladder, or — in the case of those 

 fishes in which the air-bladder is connected with the 

 gullet by an open duct — by the violent expulsion of 

 the gases of the air-bladder through this duct, some- 

 what as in coughing. In the case of the two species 

 of sea-perches (Therapon theraps and Pristipoma 

 gouraka) and of the numerous species of Scicena which 



