WORMS. 187 



notably in the molluscs, thus showing a remote relation- 

 ship between them. 



ORDER II. OLIGOCH^ET^. 



In the Oligochsetes the parapodia are lacking, and the 

 cha3ta3, which, as the name indicates, are few in number, 

 project directly from the body-wall. Appendages of all 

 kinds are usually entirely absent. A few of the group are 

 marine, more occur in fresh water, but the great majority 

 are terrestrial, and are familiarly known as 'earthworms' 

 or 'angleworms/ the latter name being given from their 

 use in baiting fish-hooks. The earthworms burrow in 

 the soil, feeding upon decaying vegetable matter in the 

 earth. They swallow earth and all, and come to the 

 surface to deposit their well-known castings. In this way 

 they work over the soil, and are of immense value to 

 agriculture, as Darwin has shown in a most interesting 

 volume on these lowly forms. Our earthworms are mod- 

 erate in size, but in Africa, South America, and Australia 

 giant earthworms, four to six feet in length and an inch 

 in diameter, occur. 



SUBCLASS II. HIRUDINEI (Leeches). 



The leeches have the body-segments ringed, so that one 

 examining the outside would conclude that there were 

 more segments than are really present. There are no bris- 

 tles on the segments, but the hinder end always bears a 

 sucking disc, while usually there is a second sucker around 

 the mouth. The body-cavity is not distinct, for by the 

 great development of the tissues it has been almost en- 

 tirely obliterated. There are two great groups of leeches 

 those with jaws around the mouth, and those which lack 

 jaws. 



