( 28 ) 



gill-cavity. This mode of respiration appears to bo a wise 

 provision of Nature, to enable flsb in trojjical eonntrics, 

 (luring periodic dry seasons or in the rains, to migrate from 

 poiul to pond in search of water wherein tlieir natural food ex- 

 ists. Also as they ascend small water-courses to breed during 

 seasons of inundations, they are always liable to have the 

 supply of water suddenly arrested, and then they regain 

 rivers, &c., through muddy channels or moist pieces of grass. 

 Thirdly, there are some fish Avhich also appear to swallow air, 

 and perhaps absorb oxygen through the skin, as the loaches, 

 CobitidiiKC, and the spincd eels, li/ti/iichoLdellidis, but no 

 special air-breathing apparatus has as yet been detected. 



^Estivation of Pish. 



XLIV. A curious phenomenon in Indian fresh-waters, 

 „ . . ,„, and one which has never been satis- 



iTistivutiou of fishes. o , •■> i-i-.i ti 



lai^torily explamed, is the sudden 

 appearance of healthy adult fish after a heavy fall of rain, 

 and in localities which fo;- months jireviously had been dry. 

 When pieces of water inhabited bj' tish yearly dry up, what 

 becomes of them? On 18th January 1809, when examining 

 this question, I was taken to a tank, of perhaps an acre 

 in extent, but which was then almost dry, having only about 

 four inches of water in its centre, whilst its circumference Avas 

 sufficiently dried to walk upon. The soil was a thick and 

 consistent bluish clay, from which, and not nearer than 30 

 paces to the water, five live fish were extracted from at 

 least tAVO feet below the surface of the mud. They consisted 

 of two of the Ophiocephaliis imnctatus, and three of tlie Illiijii- 

 choLdella aculeata. All Avere very lively and not in the 

 slightest degree torpid ; they were covered over Avitli a thick 

 adherent slime. Amongst the specimens of fish in the 

 Calcutta Museum is one of Aiiiphipiions ciichia, \Y\\\(i\\\\'i\s 

 dug up some feet below the surface of the mud, Avhen 

 sinking the foundation for a bridge. If Avhen the Avater 

 failed fish invariably died, the tanks would bo dejiopulated 

 the succeeding year, unless a fresh supply Avas obtained from 

 some other source, whilst the distance from other pieces of 

 Avater at Avhich they re-appcar excludes, in many instances, 

 the possibility of migration, Avhich must alAA'ays to a certain 

 extent be regulated by distance, time, and other local cir- 

 cumstances. Some species, especially " compound-breathers " 

 (para. XLIII), are able to live in liquid mud, Avhieh they 

 cannot employ for the purposes of aquatic respiration. Tiie 



