56 THE PHYSIOLOGY OF THE COMMON CRAYFISH. 



a broad plate, hairy 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- 



PlG. 10. — Astacusjtnviatilis. — Longitudinal section of the stomach ( x 4), 

 c, cardiac ossicle; cce, caecum ; c.p.v, cardio-pyloric valve; eg, cushion- 

 shaped surface ; Jig, hind-gut ; hp, aperture of right bile duct ; lp, 

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

 oesophagus ;p, pyloric ossicle ; pe. pterocardiac ossicles ; pp, prepy- 

 loric ossicle ; iio, urocardiac process ; v l , median pyloric valve; v\ 

 lateral pyloric valve; apposition 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 



