The same thing takes place in other tropical regions, subject to vicissitudes of draught and moisture. The Protopterus[1] which inhabits the Gambia (and which, though demonstrated by Professor Owen to possess all the essential organisation of fishes, is nevertheless provided with true lungs), is accustomed in the dry season, when the river retires into its channel, to bury itself to the depth of twelve or sixteen inches in the indurated mud of the banks, and to remain in a state of torpor till the rising of the stream after the rains enables it to resume its active habits. At this period the natives of the Gambia, like those of Ceylon, resort to the river, and secure the fish in considerable numbers as they flounder in the still shallow water. A parallel instance occurs in Abyssinia in relation to the fish of the Mareb, one of the sources of the Nile, the waters of which are partially absorbed in traversing the plains of Taka. During the summer its bed is dry, and in the slime at the depth of more than six feet is found a species of fish without scales, different from any known to inhabit the Nile.[2]
1: Lepidosiren annectans, Owen. See Linn. Trans. 1839.
2: This statement will be found in QUATREMERE'S Memoires sur l'Egypte, tom. i. p. 17, on the authority of Abdullah ben Ahmed ben Solaim Assouany, in his History of Nubia, "Simon, héritier présomptif du royanme d'Alouah, m'a assuré que l'on trouve, dans la vase qui couvre le fond de cette rivière, un grand poisson sans écailles, qui ne ressemble en rien aux poissons du Nil, et que, pour l'avoir, il faut creuser à une toise et plus de profondeur." To this passage there is appended this note:—"Le patriarche Mendes, cité par Legrand (Relation Hist. d'Abyssinie, du P. LOBO, p. 212-3) rapporte que le fleuve Mareb, après avoir arrosé une étendue de pays considérable, se perd sous terre; et que quand les Portugais faisaient la guerre dans ce pays, ils fouilloient dans le sable, et y trouvoient de la bonne eau et du bon poison. Au rapport de l'auteur de l'Ayin Akbery (tom. ii. p. 146, ed. 1800), dans le Soubah de Caschmir, près du lieu nommé Tilahmoulah, est une grande pièce de terre qui est inondée pendant la saison des pluies. Lorsque les eaux se sont évaporées, et que la vase est presque sèche, les habitans prennent des bâtons d'environ une aune de long, qu'ils enfoncent dans la vase, et ils y trouvent quantité de grands et petits poissons." In the library of the British Museum there is an unique MS. of MANOEL DE ALMEIDA, written in the sixteenth century, from which Balthasar Tellez compiled his Historia General de Ethiopia alta, printed at Coimbra in 1660, and in it the above statement of Mendes is corroborated by Almeida, who says that he was told by João Gabriel, a Creole Portuguese, born in Abyssinia, who had visited the Merab, and who said that the "fish were to be found everywhere eight or ten palms down, and that he had eaten of them."
In South America the "round-headed hassar" of Guiana, Callicthys littoralis, and the "yarrow," a species of the family Esocidæ, although they possess no specially modified respiratory organs, are accustomed to bury themselves in the mud on the subsidence of water in the pools during the dry season.[1] The Loricaria of Surinam, another Siluridan, exhibits a similar instinct, and resorts to the same expedient. Sir R. Schomburgk, in his account of the fishes of Guiana, confirms this account of the Callicthys, and says "they can exist in muddy lakes without any water whatever, and great numbers of them are sometimes dug up from such situations."
1: See Paper "on some Species of Fishes and Reptiles in Demerara," by J. HANDCOOK, Esq., M.D., Zoological Journal, vol. iv. p. 243.
In those portions of Ceylon where the country is flat, and small tanks are extremely numerous, the natives in the hot season are accustomed to dig in the mud for fish. Mr. Whiting, the chief civil officer of the eastern province, informs me that, on two occasions, he was present accidentally when the villagers were so engaged, once at the tank of Moeletivoe, within a few miles of Kottiar, near the bay of Trincomalie, and again at a tank between Ellendetorre and Arnetivoe, on the bank of the Vergel river. The clay was firm, but moist, and as the men flung out lumps of it with a spade, it fell to pieces, disclosing fish from nine to twelve inches long, which were full grown and healthy, and jumped on the bank when exposed to the sun light.
Being desirous of obtaining a specimen of the fish so exhumed, I received from the Moodliar of Matura, A.B. Wickremeratne, a fish taken along with others of the same kind from a tank in which the water had dried up; it was found at a depth of a foot and a half where the mud was still moist, whilst the surface was dry and hard. The fish which the moodliar sent to me proved to be an Anabas, and closely resembles the Perca scandens of Daldorf.
THE ANABAS OF THE DRY TANKS
But the faculty of becoming torpid at such periods is not confined in Ceylon to the crocodiles and fishes, it is equally possessed by some of the fresh-water mollusca and aquatic coleoptera. The largest of the former, the Ampullaria glauca, is found in still water in all parts of the island, not alone in the tanks, but in rice-fields and the watercourses by which they are irrigated. There it deposits a bundle of eggs with a white calcareous shell, to the number of one hundred and more in each group, at a considerable depth in the soft mud, under which, when the water is about to evaporate during the dry season, it burrows and conceals itself[1] till the returning rains restore it to liberty, and reproduce its accustomed food. The Melania Paludina in the same way retires during the droughts into the muddy soil of the rice lands; and it can only be by such an instinct that this and other mollusca are preserved when the tanks evaporate, to re-appear in full growth and vigour immediately on the return of the rains.[2]