322 



THE EARTHWORM 



feather on a central axis {long. mi/s). Finally, within the 



muscular layer and lining the ccelome is a thin peritoneal 



meiiihrane (parietal layer, compare p. 26), on the inner 



dors V 



neph 



xuh.n.vcs:. 



F1C.570. — Lumbrictis, transverse scclioniof the middle region of the body. ■ 

 circ. niHS. layer of circular muscular fibres ; c<rL coslome ; cut. cuticle ; i^ors. 7'. 

 dorsal vessel ; epid. cpiderm ; ext. nefh. nephridropore ; //.•/. layer of yellow 

 cells ; A"(c- "'wJ- longitudinal muscles ; «(•///, nepbridium ; nc^hi-osi. nephros- 

 tome ; net-:'. CO. nerve cord ; set. setai ; stih. n. vcss. sub-neural vessel ; typh. 

 typhlosole ; 7'(?«/. -■. ventral vessel! (From Parker and Haswell's Zf<7/c^', after 

 Marshall and Hurst.) 



surface of which is a very thin layer of cells the ccelonik 

 epithelium. 



A transverse section of the intestine shows an inner 

 layer of ciliated, columnar enteric epithelium (compare p. 

 log) , a thin middle layer composed of muscle-fibres and 



