THE EARTHWORM AND ITS ALLIES 



139 



This group contains several rather rare animals. One 



of the commonest is Phascolosoma, 1 which is a tough but 



smooth-skinned, cigar-shaped worm, which one can dig up 



on our sandy beaches (Fig. 125). One end is pointed ; 



from the other a great proboscis 



terminating in tentacles surround- 



ing a mouth can be extruded. 



Another species found on our 



beaches after a storm, something 



like a small cucumber in shape and 



size, has a row of bristles at each 



end, indicating its relationship 



with the bristle-bearing worms. 



This species, Echiurus, 2 is seg- 



mented when young like Nereis, 



but eventually it loses its seg- 



mentation (Fig. 12(>). Several 



species of Sipimculus are edible, 



and are held in esteem by the 



Chinese. 



To the account of the Oli- 

 gochreta above given may be 



postset 



added some statements concern- Fm ' 



one-half nat. size. 



About 

 prob., 



proboscis ; ant. set., anterior 

 seta;; post, set., posterior 

 setjB. After Greef, from Par- 

 ker and Haswell's " Text- 

 book." 



ing a group of annelids of very 

 different appearance. The leeches, 

 or " blood-suckers," are flattened 

 Avorms, Avhich, like the earthworm, 

 show metamerism ; that is, there is a repetition of the in- 

 ternal organs. They are also segmented ; that is, the 

 body has external rings, although they may be obscure. 

 One segment' does not, hoAvever, as in the earthworm, 



1 0d(TKa;\oj, sac ; <rw/xa, body. 2 e'x<s> adder ; ot)/>d, tail. 



