THE EARTHWORM AND ITS ALLIES 



139 



anksek 



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. 126). Several 

 species of Sipunculus are edible, 

 and are held in esteem by the 

 Chinese. . 



To the account of the Oli- 

 gochaeta above given may be 

 added some statements concern- 

 ing a group of annelids of very 

 different appearance. The leeches, 

 or "blood-suckers," are flattened 

 worms, which, 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, however, as in the earthworm, 



FIG. 126. Echiurus. About 

 one-half nat. size, prob., 

 proboscis; ant. set., anterior 

 setae; post, set., posterior 

 setae. After Greef, from Par- 

 ker and Haswell's " Text- 

 book." 



1 </><<r/co;Xos, sac ; aw/Lea, body. 



2 c%is, adder ; oupci, tail. 



