56 



THE PHYSIOLOGY OF THE COMMON CRAYFISH. 



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

 into the hiteral wall of the cardiac chamber. There are 

 various other smaller skeletal parts, but the most im- 



FiG. 10. — Ast/icn-fffiirititirii^. — Longitudinal section of the stomach ( x 4), 

 c, cardiac ossicle; err, cajcum ; e.p.r. cardio-pyloric valve; ct. cushion- 

 shaped surface ; /if/, hind-gfut ; Jij?, aperture of right bile duct ; Ip, 

 lateral pouch ; It. lateral teeth ; iiiff, mid-gut ; 7)it, median tooth ; «>.?, 

 oesophagus ; 7;, pyloric ossicle ; j;e. pterocardiac ossicles ; j?p, prepy- 

 loric ossicle ; lie, urocardiac process ; r', median pj'loric valve ; v^, 

 lateral pyloric valve; j", position of gastrolith; :c, 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 



