HIRU DO. 25 
mud, their natural habitation, the vessels of all should be provided. 
Likewise abundant replenishment with water at short intervals is essen- 
tial, as the copious exuviation of such animals sometimes renders it 
turbid. 
The Horse Leech is of easy preservation from its natural habits. Its 
appetite for fish, flesh, or vegetable matter, is very promiscuous ; and it 
remains long out of the water uninjured, not only resting beneath stones 
on the margin of ponds or marshes near its native haunts, but im cap- 
tivity, adhering to that portion of glass vessels above the surface of the 
water. 
Favourable opportunities, and suitable treatment, might perhaps tend 
to establish those which I have considered only varieties, to be distinct 
species, as purposed by some of the continental naturalists. 
Two small specimens, neither exceeding an inch and a half, were 
taken among others in May. A row of black spots of lighter hue ran 
down each side of the back.—Fig. 6. One of these two having crawled 
out of the vessel, its body had accidentally sundred. Ten spots were seen 
on the margin.—Fig. 7. 
The specimen which had been mutilated survived two months, when 
I thought I observed a papilla prominent on the wound. But the sub- 
sequent disappearance of the animal, induced me to conclude that it 
had fallen a victim to some one stronger of its kind. 
The restlessness of the Horse Leech is in proportion to the tempera- 
ture of the atmosphere, and the effects of hunger. No creature is more 
susceptible of cold. In the middle of summer, specimens quite torpid, 
ure found under stones beyond the margin of the waters. 
Collectors sometimes attempt to palm the Horse Leech for the Me- 
dicinal Leech upon their neighbours. I once received half a dozen from 
an apothecary in Edinburgh, desirous to know of what species they were, 
as he had been offered about fifty. These were small, dark, with black 
specks on the belly. 
The owners of lakes and marshes likewise very often conclude that 
they have discovered sources of profit from the presence of these animals, 
supposing them the medicinal species. 
D 
