56 



THE PHYSIOLOGY OF TPIE COMMON CRAYFISH. 



a broad plate, liairy on its inner surface, which enters 

 into the lateral wall of the cardiac chamber. There are 

 various other smaller skeletal parts, but the most im- 



/.; ^^V- '"•^' 



Fig. 10, — Asia CHS Jiuriat ills. — Longitudinal section of the stomach ( x 4), 

 c, cardiac ossicle; ca?, ca3cum ; c.j).}-, cardio-pyloric valve; cs. cushion- 

 shaped surface ; 7///, hind-gut ; hp. aperture of right bile duct ; Ip, 

 lateral pouch ; It, lateral teeth ; mg, mid-gut ; mt, median tooth ; ces, 

 oesophagus ; j), pyloric ossicle ; ^ic. pterocardiac ossicles ; j)!'^ prepy- 

 loric ossicle ; lie, urocardiac process ; v\ median pyloric valve; t-, 

 lateral pyloric valve; a*, position of gastrolith; zc, zygocardiac ossicle. 



portant are those which have been described; and these, 

 from what has been said, will be seen to form a sort of 

 hexagonal frame, with more or less flexible joints at the 

 angles, and having the anterior and the posterior sides 



