THE SCOLOPENDRA. 381 



The gaily worm differs from the scolopendra in hav- 

 ing double the number of feet ; the colour varies ac- 

 cording to the place of its existence, and they are gene- 

 rally found between the bark of decayed trees. Though 

 these creatures may be injurious in the tropical cli- 

 mates, in Europe they doubtless are a harmless race. 



THE LEECH. 



The history of the leech, from its beneficial influ- 

 ence, may doubtless be considered as interesting to 

 mankind : there are four different animals" of this spe- 

 cies, though only one amongst them is of essential use. 



The horse-leech, which is the largest of all the num- 

 ber, will not even adhere to the skin ; and the snail- 

 leech, which does not measure more than an inch, can- 

 not extract blood enough to answer any end : the 

 broad-tailed leech will stick but on few occasions ; but 

 the large brown leech generally produces the desired 

 effect. 



The form of the leech bears some resemblance to 

 that of a worm, and its skin is likewise composed of 

 rings, in consequence of which it can both dilate and 

 contract itself; and, when touched, does not appear 

 more than an inch in length : it has a small head, with 

 a blackish skin spotted with yellow, and a line of the 

 same running down its sides ; its mouth is formed in a 

 triangular direction, in which are placed three sharp 

 teeth, which are concealed by a pair of lips : with these 

 teeth the creature pierces through the skin ; both the 

 tongue and lips assist it in drawing the blood from the 

 wound ; and it adheres so firmly to the little orifice, 

 that, until completely gorged, it cannot be removed. 

 In this part of the world they seldom exceed four 



