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Show 466 ANN ELIDES. FAMILY II. ABRANCHIAT .lE ASETIGER.£. The second family consists of two great genera, both of which are aquatic. H1nuno, 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 exte~ding 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 creca. 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( 1 ). They have been subdivided from characters principally drawn from the organs of their mouth. In the ( 1) See Memoires pour seruir a l' Hist. Nat. des Sangues, by P. Thomas; a Me· moir ofSpix, Acad. Dav., 1813; and a third ofM. Carena, Acad. Turin., t. XXV; but especially the Systeme des .IJ.nnelides, Savigny, and the Monographie dea Hirudinea, Moquin-Tandon, Montpellier, 1826, 4to. See also Essai d'une Monographie de la famUle des Hirudinees, extracted from the Diet. des Sc. Nat. by M. de Dlainv., Paris, 1827, 8vo, and the article SA.lliGSUE of the same work, by Audouin. ABRANCHIAT.lE. 467 SANGUISUGA, Sav.( 1) 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 contains three jaws, each edge of which is armed with two rows of very fine teeth, which enables them 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 beneath. It is found in all stagnant waters. The HJEMOPsxs, Sav.(2) Differs from the preceding in the teeth of its jaws, which are few and obtuse. Ha;mop. sanguisorba, Sav.; Hirudo sanguisuga, L., Moq. Tand., pl. iv, f. 1; Car., pl. xi, f. 7 (The Horse Leach). Much larger, and entirely greenish-black. It is said to cause dangerous wounds(3). In the BnELLA, Sav.( 4) There are but eight eyes, and the jaws are completely edentated. Bd. nilotica, Eg. Annel., pl. v, f. 4. Inhabits the Nile. In the NEPHELis, Sav.( 5) There are also but eight eyes; the interior of the mouth has but (1) M. de Blainville changes this name into JATROBELL.IE. For the various medicinal Leeches see the fig. ofMessrs Carena, Acad. Turin., t. XXV, pl. xi, and Moquin-Tandon, pl. v. (2) This name is changed by M. de Blainv.ille to HYPOBDELL.IE, (3) There is a singular diversity of opinion with respect to the faculty of dr:nv. ing blood possessed by this animal. Linnreus says that nine of them will kill a horse. Messrs Huzard and Pelletier, on the contrary, in a Memoir, ad hoc, pre· sented to the Institute, and inserted in the Journal de Pharmacie, March 1825, assert that it attacks no vertebrated animal. M. de Blain ville thinks this is owing to its having been confounded with a neighbouring species, the Sangsue noire, which he makes the type of a genus called PsEunonDELLA, the jaws of which are mere folds of skin without any teeth. I think this fact worthy of examination. Both species devour the Lumbrlci with avidity. (4) M. Moquin-Tandon changes this name to LrMNATIS. (5) M. de Blain ville calls them EnPOBDELL1E. Oken had previously named them |