Even admitting the soundness of his theory, and the probability that, under favourable circumstances, the spawn in the tanks might be preserved during the dry season so as to contribute to the perpetuation of their inhabitants, the fact is no longer doubtful, that adult fish in Ceylon, like some of those that inhabit similar waters both in the New and Old World, have been endowed by the Creator with the singular faculty of providing against the periodical droughts either by journeying overland in search of still unexhausted water, or, on its utter disappearance, by burying themselves in the mud to await the return of the rains.

Travelling Fishes.—­It was well known to the Greeks that certain fishes of India possessed the power of leaving the rivers and returning to them again after long migrations[1] on dry land, and modern observation has fully confirmed their statements.  The fish leave the pools and nullahs in the dry season, and led by an instinct as yet unexplained, shape their course through the grass towards the nearest pool of water.  A similar phenomenon is observable in countries similarly circumstanced.  The Doras of Guiana[2] have been seen travelling over land during the dry season in search of their natural element[3], in such droves that the negroes have filled baskets with them during these terrestrial excursions.

[Footnote 1:  I have collected into a note, which will be found in the appendix to this chapter, the opinions entertained by the Greeks and Romans upon this habit of the fresh-water fishes of India.  See note B.]

[Footnote 2:  D.  Hancockii, Cuv. et Val.]

[Footnote 3:  Sir R. Schomburgk’s Fishes of Guiana, vol. i. pp. 113, 151, 160.  Another migratory fish was found by Bose very numerous in the fresh waters of Carolina and in ponds liable to become dry in summer.  When captured and placed on the ground, “they always directed themselves towards the nearest water, which they could not possibly see, and which they must have discovered by some internal index.”  They belong to the genus Hydrargyra, and are called Swampines.—­ KIBBY, Bridgewater Treatise, vol i. p. 143.

Eels kept in a garden, when August arrived (the period at which instinct impels them to go to the sea to spawn) were in the habit of leaving the pond and were invariably found moving eastward in the direction of the sea.—­YARRELL, vol. ii. p. 384.  Anglers observe that fish newly caught, when placed out of sight of water, always struggle towards it to escape.]

Pallegoix in his account of Siam, enumerates three species of fishes which leave the tanks and channels and traverse the damp grass[1]; and Sir John Bowring, in his account of the embassy to the Siamese kings in 1855, states, that in ascending and descending the river Meinam to Bankok, he was amused with the novel sight of fish leaving the river, gliding over the wet banks, and losing themselves amongst the trees of the jungle.[2]