110 CLASS ANNULATA. 



improperly applied to the horse-leech; on this account 

 a recent author has suggested the name of Hirudo 

 vorax, (the voracious leech,) as being more suitable to 

 its nature. 



Leeches are supposed to be very long-lived ; two were 

 preserved in confinement for eight years before they 

 died, and the well-ascertained slowness of their growth 

 seems to place their length of life beyond a doubt. 



On the head of the medicinal leech ten points 

 are arranged in the form of a horse-shoe, thus — 

 These are considered, by some authors, to be • 

 organs of sight, or eyes, while, on the other • 

 hand, it is stated by others, that they are merely 

 tubercles. Lamarck was of this opinion, and, conse- 

 quently, in describing their character, says they are 

 without eyes. 



The teeth, or rather piercers, with which the leech is 

 furnished, are three in number, of a hard gristly sub- 

 stance, and so placed, with regard to each other, as to 

 meet in the centre at equal angles : these piercers are 

 thrust into the skin when the animal attaches itself; not 

 by one plunging effort, but by constantly scratching or 

 sawing upon the surface (assisted at the same time 

 by the sucking action of the lips) ; in this manner they 

 gradually become buried in the skin, and there remain 

 as long as the creature retains its hold ; this movement 

 of the' piercers occasions the gnawing pain felt for the 

 first two or three minutes after the leech has commenced 

 operation. 



Leeches are at times so scarce and valuable, that 

 great care has been taken in preserving them in a 

 healthy state and fit for use. The principal art in 

 managing them consists in placing them in vessels 



