,
to quench their thirst and to bathe. Lurking amongst the rank vegetation
that fringes these deep pools, and hid by the broad leaves, or concealed
among the stems and roots covered by the water, there are quantities of
these pests in wait to attack the animals on their approach to drink.
Their natural food consists of the juices of lumbrici and other
invertebrata; but they generally avail themselves of the opportunity
afforded by the dipping of the muzzles of the animals in the water to
fasten on their nostrils, and by degrees to make their way to the deeper
recesses of the nasal passages, and the mucous membranes of the throat
and gullet. As many as a dozen have been found attached to the
epiglottis and pharynx of a bullock, producing such irritation and
submucous effusion that death has eventually ensued; and so tenacious
are the leeches that even after death they retain their hold for some
hours.[3]

[Footnote 1: _Hirudo sanguisorba_. The paddi-field leech of Ceylon, used
for surgical purposes, has the dorsal surface of blackish olive, with
several longitudinal striae, more or less defined; the crenated margin
yellow. The ventral surface is fulvous, bordered laterally with olive;
the extreme margin yellow. The eyes are ranged as in the common
medicinal leech of Europe; the four anterior ones rather larger than the
others. The teeth are 140 in each series, appearing as a single row; in
size diminishing gradually from one end, very close set, and about half
the width of a tooth apart. When full grown, these leeches are about two
inches long, but reaching to six inches when extended. Mr. Thwaites, to
whom I am indebted for these particulars, adds that he saw in a tank at
Kolona Korle leeches which appeared to him flatter and of a darker
colour than those described above, but that he had not an opportunity of
examining them particularly.

[Illustration: DORSAL.]

[Illustration: VENTRAL.]

Mr. Thwaites states that there is a smaller tank leech of an olive-green
colour, with some indistinct longitudinal striae on the upper surface;
the crenated margin of a pale yellowish-green; ocelli as in the
paddi-field leech; length, one inch at rest, three inches when extended.

Mr. E.L. LAYARD informs us, _Mag. Nat. Hist_. p. 225, 1853, that a
bubbling spring at the village of Tonniotoo, three miles S.W. of
Moeletivoe, supplies most of the leeches used in the island. Those in
use at Colombo are obtained in the immediate vicini