56 THE PHYSIOLOGY OF THE COMMON CRAYFISH. 



a broad plate, hairy on its inner sui-face, which enters 

 into the lateral wall of the cardiac chamber. There are 

 various other smaller skeletal parts, but the most im- 



P:,P- 



hp. my- 



Fig. 10. — Astacnsfluviatn'is. — Longitudinal section, of the stomach ( x 4). 

 c, cardiac ossicle; ca, cajoum ; c.p.v, oardio-pyloric valve; cs, cuahion- 

 shaped surface ; lig, hind-gut ; hj>, aperture of right bile duct ; Ip, 

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

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

 loric ossicle ; vc, urocardiac process ; i', median pyloric valve j r', 

 lateral pyloric valve; a;, position of gastrolith; zc, zygooardiao 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 



