302 ANNUL AT A. 



FAMILY II. 



ABRANCHIATA ASETIGERA. 



The second family consists of two great genera, both of which 

 are aquatic. 



HiEiTDo, Lin. 



Leeches have an oblong-, sometimes depressed, transversely plicated body; 

 the mouth is encircled by a lip, and the posterior extremity furnished with 

 a flattened disk, both of which are well adapted for adhering to bodies by 

 a sort of suction, and are the principal org-ans of locomotion possessed by 

 these animals; for after extending- itself, the Leech fixes its anterior extre- 

 mity and approximates the other, which in its turn adheres, to allow the for- 

 mer to be carried forward. In several we observe on the under part of the 

 -body two series of pores, the orifices of as many small internal pouches, 

 considered by some naturalists as organs of respiration, although they are 

 usually filled with, a mucous fluid. The intestinal canal is straight, inflated 

 from space to space for two-thirds of its length, where there are two cjeca. 

 The blood swallowed is preserved there, red and unchanged, for several 

 weeks. 



Several of them form their eggs into a cocoon, and envelope them with 

 a fibrous excretion. 



They have been subdivided from characters principally drawn from the 

 organs of their mouth. In the 



Sanguisuga, Sav. 



Or the Leech properly so called, the superior lip of the anterior cup or 

 sucker is divided into several segments; the aperture is transverse and con- 

 tains three jaws, each edge of which is armed with two rows of very fine 

 teeth, which enables it to penetrate] through the skin without causing 

 a dangerous wound. It is marked with ten small points, considered as eyes. 



We all know the medicinal or Common Leech — Hirudo medicinalis, L., 

 that useful instrument for the local abstraction of blood. It is usually 

 blackish, with yellowish streaks above, and yellowish with black spots be- 

 neath. It is found in all stagnant waters. The remaining divisions are 

 Hxmopsis (The Horse Leech), Bdella, Nephelis, &c. &c. 



GoRDius, Lin. 



The body resembling a thread, the only mark of the articulations being 

 slight, transverse plicae; it has neither feet, branchiae, nor tentacula. Inter- 

 nally, however, a nervous system is perceptible in a knotted cord. Perhaps 

 it will be necessary in the end to place them among the cavitary Intestina, 

 like the Nemertes. 



