HIRUDO. 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 in 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, 

 are 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. 



