CLASS VI. ANNELIDA: OEDER 4. SUCTORIA. 619 
THE LEECH. 
ORDER 4. SUCTOEIA. 
The animals belonging to tliis order, of wliicli the Common Leech is a familiar example, are 
characterized by the total deficiency of any lateral appendages, tbeir motions being effected by 
undulations of the body while swimming, or by tbe alternate attachment of the sucking discs 
with which, tbe two extremities of their bodies are usually furnished. Tliejr all apj)ear to live 
by sucking the blood of other animals, and, for this purpose, the mouth of the leech is furnished 
witli an apparatus of horny teeth, by which they bite through the skin. There are several species, 
nearly all of which are hermaphrodite. The deposition of the eggs is attended with some very 
singular circumstances. At the period of oviposition a peculiar gelatinous band is produced 
round the anterior part of the body. The leech lays its eggs in this gelatinous matter, and 
when all are deposited, it withdraws its body from the band, which then closes up, and forms 
a complete capsule, within which the eggs are inclosed. It appears, however, that the leech 
also sometimes produces a compound egg, formed of a transparent membrane, full of a liquid in 
which little globules soon begin to appear; these globules, are, in fact, so many germs of leeches, 
and during development take the form of little worms, which soon leave the egg by an opercular 
hole at its extremity. 
The use of the Common Leech, Sanguisuga officinalis, for medical purposes is enormous ; 
three millions are annually used in Paris, and one hundred millions in France ; seven millions 
two hundred thousand are annually imported by four dealers in London. The English leeches 
are chiefly derived from Sweden, Poland, and Hungary; the French from the frontiers of 
Turkey and Russia. 
The small leeches, about an inch and a half long, which infest damp places in Ceylon, often 
creep upon the legs of travelers, who are first w^arned of their presence by the flow of blood 
through their clothes. The soldiers of Napoleon in Egypt were tormented by leeches thronging 
the pools, which fixed themselves in their mouths and nostrils as they stooped to drink. 
The species of the genus Piscicola live as parasites on fresh-water fishes. 
The animals of the genus Si^mnculus and their allies, form the order of Gephyrca of some 
naturalists ; they are inarine, their bodies are cylindrical, and their habits are similar to those 
of the lob-worm. They are destitute of eyes and other organs of sense. 
