22 



BRITISH TUXIC ATA. 



rim open in front. The oesophagus is distinctly marked; 

 it is a rather short constricted tube stretching from 

 the ventral or anterior extremity of the stomach, 

 which is a large elliptical organ, somewhat laterally 

 compressed, tying transversely near to the bottom of 

 the pallia! cavity, to the left wall of which it is adhe- 

 rent. The posterior extremity of the branchial sac 

 overlies the right side of the stomach. The intestine 

 at its origin is nearly as wide as the stomach ; it 

 passes from the dorsal end of that organ, and, bending 



FIG. 31. Biliary ducts in Corella parallelogramnm. x. about 30. (Kechicecl 

 one-half from drawing made with 1 inch object-glass.) 



backwards and downwards, courses along the lower 

 mar-gin of the stomach at the bottom of the pallial 

 chamber ; it then passes up the ventral margin in a 

 straight line adherent to the branchial sac until it 

 reaches the cloaca situated at the base of the exhalant 

 tube, where, contracting a little, it terminates. The 

 anal orifice is bordered with a smooth, wide, reflected, 

 lobed rim. 



The mucous membrane lining the stomach is thick 

 and is thrown into strong, mostly longitudinal wrinkles, 

 which are arranged with some degree of regularity. 



