WATERS OF WESTERN INPIA. 227 



Of freshwater Crustacea the prawn is apparently identical with 

 that of the Deccan and Konkan, but crabs are much less common 

 here than in those provinces ; I do not know why. 



To make up for this to the birds and fishes, some of the fresh- 

 water molluscs (gasteropoda) occur in vast numbers in particular 

 tanks and marshes, especially in the North- Western plains. The 

 Uniouidas, however, are not abundant, apparently sticking chiefly to 

 running water and open gravelly or sandy bottoms. Now few of the 

 tanks have sandy bottoms, unless occasionally iu some one corner 

 end of the lakes ; I think that the Nalof Viramgaum is the only one 

 that is not marshy or weedy all round. Accordingly, I have found 

 dead shells of a small Unio on its beach. In the eastern streams 

 there seem to be the same two species as in the former provinces, but 

 they do not abound. 



During the hot weather the water of some tanks and lakes is 

 affected, by some cause unknown to me (probably the liberation of 

 gases from the mud), in such a manner that all kinds of fish rise 

 and float gasping on the surface, and eventually die in great num- 

 bers. I have described this phenomenon, as witnessed by me on the 

 Little Bokh (a lake of the Ahmedabad district), for the Report on 

 the London Fisheries Exhibition. The fish that die are left to 

 carrion fowls ; but those only moribund are captured in great num- 

 bers, and eaten without any ill result. I have repeatedly eaten 

 them myself, and found them in excellent condition. The cause 

 of death appears to be asphyxia, and not specific poisoning. I 

 have mislaid my notes, but to the best of my memory the Ophioce- 

 phali are not affected ; neither is any aquatic reptile or insect. The 

 prawns do not frequent the tanks, and I do not think that the 

 " hot water/' as the natives call it, is ever observed on any river. 

 It is well known that many bottom fish can be much inconveni- 

 enced by the mere stirring up of the mud, as by the passage of 

 cattle or elephants through a muddy stream or tank, but I have not 

 been able to connect the phenomenon now described with anything 

 of that sort. It generally lasts for several days, but may be 

 confined to a small part of a tank without visible reason for the 

 restriction. 



The freshwater of Kattywar are not materially different from 

 those of Gujarat, except that there are no large rivers, few small 

 ones, and by no means so many tanks as on the mainland. The 

 chain of lakes and marshes of which the Nal of Viramgaum is the 



