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]

[Footnote 1:  A knowledge of this fact was turned to prompt account by Mr. Edgar S. Layard, when holding a judicial office at Point Pedro in 1849.  A native who had been defrauded of his land complained before him of his neighbour, who, during his absence, had removed their common landmark by diverting the original watercourse and obliterated its traces by filling it to a level with the rest of the field.  Mr. Layard directed a trench to be sunk at the contested spot, and discovering numbers of the Ampullaria, the remains of the eggs, and the living animal which had been buried for months, the evidence was so resistless as to confound the wrongdoer, and terminate the suit.]

[Footnote 2:  For a similar fact relative to the shells and water beetles in the pools near Rio Janeiro, see DARWIN’S Nat.  Journal, ch. v. p. 90.  BENSON, in the first vol. of Gleanings of Science, published at Calcutta in 1829, describes a species of Paludina found in pools, which are periodically dried up in the hot season but reappear with the rains, p. 363.  And in the Journal of the Asiatic Soc. of Bengal for Sept. 1832, Lieut.  HUTTON, in a singularly interesting paper, has followed up the same subject by a narrative of his own observations at Mirzapore, where in June, 1832, after a few heavy showers of rain, which formed pools on the surface of the ground near a mango grove, he saw the Paludinae issuing from the ground, “pushing aside the moistened earth and coming forth from their retreats; but on the disappearance of the water not one of them was to be seen above ground.  Wishing to ascertain what had become of them, he turned up the earth at the base of several trees, and invariably found the shells buried from an inch to two inches below the surface.”  Lieut.  Hutton adds that the Ampullariae and Planorbes, as well as the Paludinae, are found in similar situations during the heats of the dry season.  The British Pisidea exhibit the same faculty (see a monograph in the Camb.  Phil.  Trans. vol. iv.).  The fact is elsewhere alluded to in the present work of the power possessed by the land leech of Ceylon of retaining vitality even after being parched to hardness during the heat of the rainless season.  Vol.  I. ch. vii. p. 312.]