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 coelome, lined by a thin cellular membrane, 

 the peritoneum or ccelomic epithelium, and rilled with a fluid, the 

 coelomic fluid, containing colourless corpuscles. The ccelome is 

 divided into a series of chambers corresponding to the segments 



dnrs \ f 



typh 



cut 



epid 



neph 



neph rost 



71. CO 



set 



vent, v 



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

 circular muscular fibres ; ccel. cffilome ; cut. cuticle ; dors. v. dorsal vessel ; epid. epidermis ; 

 ext. neph. nephridiopore ; hep. layer of chloragen cells ; long. mus. longitudinal muscle ; 

 neph. nephridium ; nephrost. nephrostome ; n. co. nerve-cord ; set. setse ; sub. n. vess. 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 

 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 (ces), which extends through about seven 



