446 



ZOOLOGY 



SECT. 



these sacs are enlarged and glandular, and receive the special name 

 of capsulogenous glands. 



The enteric canal (Fig. 366) is, as in Nereis, a tube which 

 runs through the entire length of the body from the mouth at the 

 anterior to the anus at the posterior end. As in the case of Nereis, 

 it lies in a cavity, the ccelome, lined by a thin cellular membrane,' 

 the peritoneum or coelomic epithelium, and filled with a fluid, the 

 coelomic fluid, containing colourless corpuscles. The coelome is 

 divided into a series of chambers corresponding to the segments 



dors v 



lypk 



neph -; 



neph rost 



n.co 



set 



sub.n.ress 



FIG. 365.X.umbricus, transverse section of the middle region of the body, circ mus layer of 

 circular muscular fibres ; cael. coelome ; cut. cuticle ; dors. . dorsal vessel ; epid epidermis 

 ext. nepfi . nephndiopore ; hep. layer of chloragen cells; long. mus. longitudinal muscle- 

 nepti nepnndiiim ; nephrost. nephrostome ; n. co. nerve-cord ; set. setre ; sub. n ress sub- 

 neural vessel ; typh. typhlosole : vent. v. ventral vessel. (After Marshall and Hurst.) 



by a series of delicate transverse partitions, the septa or mesenteries, 

 consisting of folds of the peritoneal membrane enclosing muscular 



f*1 O 



fibres. 



The mouth leads into a small buccal cavity. This is followed by 

 a much larger, thick-walled, rounded chamber, the pharynx (ph.). 

 From the wall of the pharynx there run outwards to the body-wall 

 a number of radially arranged bundles of muscular fibres which, 

 when they contract, draw the pharynx backwards, and at the same 

 time dilate it. Behind the pharynx follows a comparatively 

 narrow tube, the oesophagus (CBS), which extends through about seven 



