Fig. 268. — A skate,'dissected to show its skeleton and the position of 

 the alimentarytcanal in its abdominal cavity. — From Thomson. 



c, Coracoid region of pectoral girdle; h.br., basibranchial cartilage; A.m., hyo- 

 mandibular cartilage; M., cartilage of lower jaw; nt.pt., mesopterygiurn ; 

 mt.pt., metapterygium ; B.C., nasal capsule ;/>.;«. , propterygium ; p.q., carti- 

 lage of upper jaw (palato-ouadrate) ; pu., ischiopubic bar of pelvic girdle; 

 s.t., sensory tubules in the skin ; s.v., spiral valve ; sc, scapula ; st., stomach ; 

 zi.pl., fused vertebra:. 



376 



