tires 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, diverting the original watercourse and obliterating its traces
by filling it up 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 wrong-doer, 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.
99. 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 Society 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, wherein June, 1832, after a few heavy showers of rain, that
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_ exibit 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