24 HIRUDO. 
above two inches and a half, proved, appearing in general the soundest 
of any of the leeches, particularly embarrassmg. The body was round, 
deeply annulated, of dusky reddish-brown, with ten marginal specks on 
the anterior. This leech fed readily on fish, and it devoured a specimen 
of the Hirudo octo-oculata. In common with all the specimens of the 
sanguisuga, it frequently left the water. With the lapse of seven months 
the colour had become dull green, with some black spots on the under 
surface ; and in a year from the date of its capture, it had become quite 
green, the same spots still remaining.—Fig. 5, back ; 4, belly ; 5, head, 
enlarged. 
This is an active, bold, and clever animal, frequently crawling out 
of the water, and apparently always ready to quit its vessel. None of 
the tribe surpasses it in voracity. Few animal substances are rejected. 
All kinds of fish, dead or alive, seem acceptable. Penetrating the cavity 
of the larger fresh-water shells, the Horse Leech takes up a permanent 
dwelling there, until emptying them of their contents, should it be able. 
Several of this and the preceding species, the octo-oculata, having been col- 
lected from the same place, one of the latter, half swallowed by a Horse 
Leech scarcely double its size, was discovered struggling for liberty. But 
its ferocious enemy, adhering firmly by the sucker, and undulating its 
body in the water, as if to aid deglutition, occupied three hours in finish- 
ing its task,—when it appeared much distended by so copious a repast. 
Another attempted to devour a dead leech of a different kind, absorbing 
the smaller extremity here, as the former did with its living companion ; 
but the latter proved too large for its gullet. Considering the strength 
of the prey, indeed, and the adhesion, it appears a hardy effort of leeches 
to devour each other, unless under great disparity of size. 
A quantity of sand and rocky pellets are often discharged by these 
animals when recently taken, which may be perhaps ascribed to the 
nature of the creatures swallowed entire along with them. 
Leeches seem to be readily injured by excesses in feeding. Adhesion 
of the sucker becomes impaired ; and knots or enlargements of the body, 
indicate a distempered condition. They are then benefited by crawling 
through clefts and crevices, or among stones, with which last, and with 
