322 



THE EARTHWORM 



CHAP. 



feather on a central axis (long. mus). Finally, within the 

 muscular layer and lining the coelome is a thin peritoneal 

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



(Iqrsv 

 typh 



Tl£ph 



eet.nepTv 



nep7iro.it 



n.co 



sub.n.ves. 



coel 



Fig. 78. — Lumhricus, transverse section lof the middle^egion of^the body-j -^^ 

 circ, mus. layer of circular muscular fibresj; cceI. coelome ; cut. cuticle ; dors. v. 

 dorsal vessel ; epid. ejjiderm ; ext. neph. nephridropore ; hep. layer of yellow 

 cells ; long. tnus. longitudinal muscles ; nepk. nephridium ; nephrost. nephros- 

 tome ; nerv. CO. nerve cord ; set. setse ; sub. n. vess. sub-neural vessel ; typh. 

 typhlosole ; vent. v. ventral vessel. (From Parker and Haswell's Zoology^ after 

 Marshall and Hurst.) 



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

 epithelium. 



A transverse section of the intestine shows an inner 

 layer of ciliated, columnar enteric epithelium (compare p. 

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



