ABRANCHIATA. 373 



Another of greater length, was seized by the middle, 

 but as it could not be swallowed in this position, and 

 would not bend, it was dragged to the hole, but strik- 

 ing at the mouth, the decaying bark gave way and 

 was swallowed. Occasionally the Worm raised its 

 head, to seize something above the surface, or to ex- 

 plore, as a caterpillar will do at the end of a stick, and 

 at such times the mouth and fleshy lip were very visi- 

 ble. It at length got hold of a pebble, thicker than 

 itself, and drew it into the hole, probably to seal up 

 the entrance as a protection, for it did not again 

 appear. 



The Leeches (Hirudo*) are of a lengthened form, 

 generally flattened, marked with very many trans- 

 verse wrinkles. At each extremity is a fleshy disk, 

 which acts as a sucker in progression; the head being 

 stretched forward to its fullest extent, the fore- 

 sucker is attached ; the rings are powerfully contract- 

 ed, and the hind-sucker attached near the former, 

 which is then loosened, and thrust forward as before. 

 The Leech, however, can swim with much elegance, 

 though not with rapidity ; this is performed by 

 quick serpentine waves perpendicularly, the body 

 being flattened into a thin band. The instinct which 

 induces the Leech so greedily to suck the blood of other 

 animals, has been turned by man into a very valuable 

 means of alleviating human suffering. Its mouth, 

 situated in the middle of the front sucker, has three 

 little teeth placed triangularly, each with a saw-like 

 edge : and when the action of the sucker has made 

 * Their ancient Latin name. 



