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MIGRATION OF FISHES OVER LAND.
Opinions of the Greeks and Romans.
It is an illustration of the eagerness with which, after the expedition of Alexander the Great, particulars connected with the natural history of India were sought for and arranged by the Greeks, that in the works both of ARISTOTLE and THEOPHRASTUS the facts are recorded of the fishes in the Indian rivers migrating in search of water, of their burying themselves in the mud on its failure, of their being dug out thence alive during the dry season, and of their spontaneous reappearance on the return of the rains. The earliest notice is in the treatise of ARISTOTLE De Respiratione, chap. ix., who mentions the strange discovery of living fish found beneath the surface of the soil, [Greek: ton ichthuon oi polloi zosin en te ge, akinetizontes mentoi, kai euriskontai oruttomenoi]; and in his History of Animals he conjectures that in ponds periodically dried the ova of the fish so buried become vivified at the change of the season. HERODOTUS had previously hazarded a similar theory to account for the sudden appearance of fry in the Egyptian marshes on the rising of the Nile; but the cases are not parallel. THEOPHRASTUS, the friend and pupil of Aristotle, gave importance to the subject by devoting to it his essay [Greek: Peri tes ton ichthyon en zero diamones], De Piscibus in sicco degentibus. In this, after adverting to the fish called exocoetus, from its habit of going on shore to sleep, [Greek: apo tes koites], he instances the small fish ([Greek: ichthydia]), which leave the rivers of India to wander like frogs on the land; and likewise a species found near Babylon, which, when the Euphrates runs low, leave the dry channels in search of food, “moving themselves along by means of their fins and tail.” He proceeds to state that at Heraclea Pontica there are places in which fish are dug out of the earth, ([Greek: oryktoi ton ichthyon]), and he accounts for their being found under such circumstances by the subsidence of the rivers, “when the water being evaporated the fish gradually descend beneath the soil in search of moisture; and the surface becoming hard they are preserved in the damp clay below it, in a state of torpor, but are capable of vigorous movements when disturbed. In this manner, too,” Theophrastus adds, “the buried fish propagate,