NO. 9 MUSCULATURE OF THE BLUE CRAB COCHRAN 67 



XF. Posterior mesopyloric ossicles. One pair. — These ossicles lie 

 directly below the preceding. They are roughly crescentic in shape and 

 are connected by a thin membrane. (Figs. 25 C, 26.) 



XVI. Uro pyloric ossicles. One pair. — These very slender, angu- 

 larly-bent ossicles are found behind the posterior mesopyloric ossicles 

 in the roof of the pyloric region, now forming the posterior termina- 

 tion of the stomach. (Figs. 25 B, 26.) 



PV. Pyloric valves. One pair. — These valves project posteriorly 

 from the cartilagelike tissue which lies posteriorly behind the uro- 

 pyloric ossicles (XVI) in the dorsal wall of the pyloric region. (Fig. 

 25, B.) 



The ventral wall of the pyloric foregut bears the following ossicles : 



XVII. Antero-inferior pyloric ossicle. Single. — This median rhom- 

 boid plate is transversely widened and lies immediately in front of the 

 ampullae. Its widest base is anteriorly in contact with the cardio- 

 pyloric valve. (Fig. 25 C.) 



XVIII. Pre-ampullary ossicles. One pair. — These two very small 

 ossicles project from the region just behind the outer border of the 

 antero-inferior pyloric ossicle and a short distance in front of the 

 pyloric ampullae. (Figs. 25 C, 26.) 



XIX. Postero-inferior pyloric ossicle. Single. — This small bow- 

 shaped ossicle lies behind the inter-ampullary groove. It is not heavily 

 calcified and therefore is not very apparent at first glance. ( Fig. 25 C. ) 



XX. Anterior supra-ampullary ossicles. One pair. — Each one of 

 this pair of ossicles is a small semicircular, heavily calcified projection, 

 which appears just below and in contact with the lateral cardiopyloric 

 ossicle and behind the supra-ampullary ossicle. (Figs. 25 C, 26.) 



XXI. Middle supra-ampidlary ossicles. One pair. — Each one of this 

 pair of short, straight ossicles lies in a vertical position below the pre- 

 ceding and above the ampullae. (Fig. 26.) 



XXII. Posterior supra-ampidlary ossicles. One pair. — These semi- 

 circular ossicles lie close together below the ampullae, and terminate 

 the series of ossicles supporting the pyloric region posteriorly. (Fig. 

 26.) 



The following ossicles occur in the pleuropyloric walls : 



XXIII. Anterior pleuropyloric ossicles. One pair. — This very heav- 

 ily calcified, triangular structure projects strongly from the side wall 

 of the stomach in front of the anterior mesopyloric ossicle (XIV). 

 It is continued as a long forked calcareous projection leading forward 

 and downward externally along the stomach wall. (Fig. 26.) 



XXIV. Middle pleuropyloric ossicles. One pair. — Attached to one 

 of the forks of the calcareous projection of the preceding ossicle is 



