ORDER ANNULATA APODA. 103 



them in their motions, and which may, consequently, 

 be considered as supplying the place of feet ; but those 

 we have yet to notice have no similar appendages, and, 

 therefore, they are called footless. They are all very 

 lively in their movements, and live either in moist earth, 

 or the mud at the bottom of ponds. We find among 

 the footless Annulata two well-known genera, namely, 

 the Earth-worm and the Leech. 



The Common Earth-Worm, 

 {Lumbriciis terrestris.) 



The body of the Earth-worm is composed of a great 

 number of narrow rings, and along each side are 

 four rows of very small, short, silk-like bristles, of a 

 substance partly horny and partly shell-like. These 

 bristles are placed on the edges of the rings, and it 

 is by the alternate contraction and expansion of these 

 rings that the worm is enabled to move along, the little 

 bristles acting like hooks, and so forming various fixed 

 points of resistance or fulcra, upon which the animal 

 can rest at each movement forwards. The organization 

 of the Earth-worm is very simple, the intestinal canal 

 for the food being a simple straight tube, except in one 

 part of its length, where a kind of gizzard is found, 

 which answers the purpose of a stomach. It is sup- 

 posed to feed upon the vegetable substances it finds in 

 he earth. 



The hole, or burrow, formed in the earth by the worm, 



nas always two openings, one by which it enters, and by 



^^hich it throws out the dirt which is removed during 



'^^e progress of its excavation, and the other by which 



times leaves its burrow, so that the hole made 



