xnt 



PHYLUM CHORDATA 



267 



elevators which raise, and depressors which lower, a part, such as 

 the^ lower jaw. The names of the muscles may have reference to 

 their position, e.g. pectoralis (pet.), the principal muscle of the chest ; 



FIG. 939. Rana esculenta. The muscles from the ventral aspect. On the left side (right of 

 figure) many of the superficial muscles have been cut and reflected to show the deep layer. 

 add. brev. adductor brevis ; add. long, adductor longus ; add. mag. adductor magnus ; del. 

 deltoid ; ext. cr. extensor cruris ; ext. trs. extensor tarsi : FE. femur ; gn. hy. genio-hyoid ; 

 gstr. gastrocnemius ; hy. gl. hyoglossus ; ins. ten. inscriptio tendinea ; I. alb. linea alba ; 

 my.hy. mylo-hyoid ; obi. int. obliquus internus ; obi. ext. obliquus externus ; o.st. omoster- 

 num ; p. c. hy. posterior cornu of hyoid ; pet. pectoralis ; pctn. pectineus ; per. peronseus ; 

 ret. abd. rectus abdominis ; rect. int. maj. rectus internus major ; reel. int. min. rectus Internus 

 minor ; sar. sartorius ; sb. mi. sub-mentalis ; sem. ten. semi-tendinosus ; tib. ant. tibialis 

 anticus ; tib. post, tibialis po,sticus ; TI. FI. tibiofibula ; vqst, int. vastus internus ; x. st. 

 .xiphisternum. 



