278 THE ANATOMY OF INVERTEBRATED ANIMALS. 



pyloric end of the stomach, and their insertion into the pylo- 

 ric ossicle and the wide posterior part of the postero-lateral 

 pieces. 



Fig. 73.— Astacus.— Upper Figure: Longitudinal Section of Stomach.— A, anterior 

 gastric muscle ; B, posterior gastric muscle ; CE\ oesophagus ; P, pylorus ; ca, 

 cardiac ossicle; ca'. its urocardiac process; ac, urocardiac tooth; py, py- 

 loric ossicle ; the oblique bar, extending from the end of the cardiac to the pylo- 

 ric, is the pre-pyloric ossicle ; pt, pterocardiac ; se, postero-lateral cardiac, with 

 its great tooth, cc ; £, small inferior tooth ; c, cardio-pyloric valve ; b, infero- 

 median pyloric ridge ; a, lateral pyloric ridge ; d, superior pyloric ridge ; vp, 

 uro-pyloric ossicle ; x y, line of section ; the anterior face of the posterior segment 

 being shown in the lower figure. 



From the attachment of these muscles it is clear that their 

 action must, in a general way, resemble that produced by 

 pulling upon the cardiac and pyloric pieces when the stomach 

 is removed from the body. Now, the result of doing this is 

 that, the cardiac and pyloric pieces being divaricated, the 

 pre-pyloric ossicle assumes a vertical position, and the uro- 

 cardiac tooth turns downward and forward. At the same 

 time the antero-lateral or pterocardiac pieces are pulled back- 

 ward, and, owing to their oblique articulation with the car- 



