466 ANNELIDES. 



FAMILY II. 



ABRANCHIATiE ASETIGERtE. 



The second family consists of two great genera, both of 

 which are aquatic. 



HiKUDo, 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 organs 

 of locomotion possessed by these animals; for after extending itself, 

 the Leech fixes its anterior extremity and approximates the other 

 which in its turn adheres to allow the former 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 

 caeca. The blood swallowed is preserved there, red and unchanged, 

 for several weeks. 



The ganglions of the nervous cord are much more separate than 

 in the Lumbrici. 



The Hirudines are hermaphrodites. A large penis projects from 

 under the anterior third of the body, and the valve is a little further 

 behind. 



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

 them with a fibrous excretion(l). 



They have been subdivided from characters principally drawn 

 from the organs of their mouth. In the 



(1) %&& M^moires pour servir a I' Hist. Nat. des Sangus,hyV. Thomas; a Me- 

 moir ofSpix, Acad. Bay., 1813; and athird of M. Carena, cAcad. Turin., t. XXV; 

 but especially the Systeme des AnnHides, Savigny, and the Monographie des Hiru- 

 dines, Moquin-Tandon, Montpellier, 1826, 4to. See also Essai d'une Monographie 

 delafamille des Hirudinees, extracted from the Diet, des Sc. Nat. by M. de Blainv., 

 Paris, 1827, 8vo, and the article Sakgsue of the same work, by Audouin. 



