286 DR. F. DAY ON INDIAN FRESHWATER FISHES. [May 14, 



become depopulated. Again, the distance from other pieces of 

 water at which they reappear, excludes in many instances the pos- 

 sibility of migration, which must always, to a certain extent, be 

 regulated by distance, time, and other local circumstances. 



I have already shown that some species can live in liquid mud, 

 which they cannot employ for the purposes of aquatic respiration. 

 The question now arises whether, during the drought when food 

 and water fail, fish do not altogether hybernate, or rather aestivate, 

 until the return of a more favourable season. From their low 

 state of organization, they would undoubtedly be more likely to 

 become torpid during the heat than many other animals possessed 

 of a higher vitality, which have been proved to do so, such as the 

 Batrachians, the Emys, the Lepidosiren annectens, some of the 

 Crocodiles, and others, as well as moUusks and land-snails. 



The natives of India believe this to be the case ; and many of 

 them, and some few Europeans, have asserted that they have 

 actually seen fishes thus exhumed alive from the bottoms of perfectly 

 hard dry tanks, and subsequently resuscitated by placing them in 

 water. That they are capable of burrowing is easily proved by 

 watching them in an aquarium, and is especially exemplified in the 

 c&s,&o^ &sr[iaX[Y,02ic\\{Platacanthus madrasj)atensis, Day), which, if 

 the water is being changed, or anything occurs to alarm it, dives 

 down into the sand, and totally disappears from view with the 

 greatest rapidity ; and so well does it conceal itself that, on several 

 occasions, when the sand was removed from the aquarium, it was 

 most difficult to find and capture it. It evidently employs its armed 

 pectoral fin for the purpose of diving. The Etropli and many 

 others also conceal themselves very rapidly and effectually when 

 alarmed. 



It appears probable that, as the water in the tanks becomes low, 

 the fishes congregate together in holes and places in which some 

 water still remains, where they may frequently be seen in numbers 

 huddled together with only sufficient water to cover their dorsal 

 fins. If disturbed they dive down into the thick mud, and if 

 either a drag or cast-net be then employed it is probable that 

 nothing will be obtained. The only way of catching fish at this 

 time is to leave the net down and walk about in the surrounding 

 thick mud. In the course of time they must come to the surface 

 to breathe, and then they fall an easy prey. As the water gradu- 

 ally evaporates, the fishes appear to become more and more sluggish, 

 and finally, there is every reason to believe, bury themselves in the 

 soft mud, and in a state of torpidity await the return of their 

 natural element. This would, if proved, only show the correctness 

 of Dr. Hunter's assertion*, "that hybernation is apparently due to 

 a suspension of the faculties of animals by nature during such 

 seasons, and in such situations, that a supply of food is not ob- 

 tainable." 



In Europe it is known that fish hybernate during the winter 

 months. Eels bury themselves twelve or sixteen inches deep in the 

 * Observations ou Parts of the animal Economy, p. 88. 



J 



