HABITS OF THE LEECH. 189 



the ground, fasten on to the legs of man or beast, and gorge 

 themselves with blood. In every leech there is a posterior 

 attaching sucker, while the mouth in the ecto- parasitic 

 types is more literally suctorial. By attaching the head- 

 end and loosening the tail, then fixing the tail and' extending 

 the anterior region, many leeches move very quickly and 

 deftly, while at other times, or in other forms, the mode of 

 locomotion is by graceful serpent-like swimming, or by 

 gentle gliding after the manner of snails. The hungry 

 horse-leeches, " whose daughters cry Give, Give," are species 

 of Hcemopis, greedily suctorial though their teeth are too 

 small to be useful in blood-letting ; but the popular name is 

 also applied to species of the common genus Aulastoma, 

 whose members are carnivorous. Other common leeches 

 are species oiNephelis, predacious forms with indiscriminating 

 appetites, and the little Ckpsine, also common in our ponds, 

 notable for its habit of carrying its young about on its belly. 

 Numerous marine forms prey upon fishes and other animals, 

 e.g., the " skate-sucker " Pontobdella, with leathery skin 

 rough with knobs, and Branchellion on the Torpedo, 

 remarkable for numerous leaf-like respiratory plates on the 

 sides of its body. Perhaps the strangest habitat is that 

 of Lophobdella, which lives on the lips and jaws of the 

 crocodile. 



Type. The Medicinal Leech {Hirudo medicinalis). 



This is the commonest and most familiar of leeches, once 

 so constantly used in the practice of medicine that_ leech 

 became synonymous with medical practitioner. It lives in 

 ponds and sluggish streams, and though not common in 

 Britain, is very abundant in many regions of the Continent, 

 where leech farms, formerly of great importance, are still to 

 be seen. Leeches feed on the blood of fishes, frogs, and the 

 like, and are still caught in the old fashion on the bare legs 

 of the callous collector. As animals are naturally averse to 

 blood-letting and hard to catch, leeches take as much as 

 they can hold when they are at it, and once gorged with 

 blood will keep on slowly digesting for many months, it 

 may be indeed for a year. Watched in a glass jar, the leech 



