277 



Fig. 204. — Sections of part of the alimentary canal of Donax. — After Barrois. 

 Yapp, An Introduction to Animal Physiology, 1939. Clarendon Press, Oxford. 



A , Longitudinal section ; B, transverse section of caecum. 



cc.m , caecum ; cil., ciliated epithelium ; est., crystalline style ; g.s., gastric shield ; int., intestine; 



M., mouth; 0^., oesophagus ; si., stomach. 



Fig. 205. — The structure of Anodonta. — After Rankin. 



a.a.. Anterior adductor; c.p.g., cerebral or cerebropleural ganglia; st., stomach; t-., ventricle, with an 

 auricle opening into it ; k., kidney, above which is the posterior retractor of the foot ; r., rectum ending 

 above posterior adductor ; v.g., visceral gangha with connectives (in black) from ccrebropleurals ; 

 g., gut coiling in foot ; p.g., pedal ganglia in foot, where also are seen branches of the anterior aorta 

 and the reproductive organs ; l.p., labial palps behind mouth. \i the posterior end the exhalant 

 (upper) and inhalant (lower) siphons are seen. 



