MUSCULAR SYSTEM. 



115 



where the uniform character persists both dorsally and ventrally, 

 retains throughout more primitive relations than does the ventral, 



FIG. 99. THE MUSCULATURE OF Sircdoii ji/^'/f>rmis. (From the ventral side.) 



0, outermost layer of the external oblique, passing into the fascia, which is shown cut 

 through at F ; Ob, second layer of the same muscle ; Re, rectus abdominis, 

 passing into the visceral musculature (sternohyoid) at He 1 , and into the pector- 

 alis major at P ; JIh, J/A 1 , anterior and posterior portions of the mylohyoid, 

 which is cut through in the middle line, and removed on the left side, so as to show 

 the proper visceral musculature ; '''', Ci, Ci { . external and internal ceratohyoid : 

 the former is inserted on to the hyoid (Hy) ; Add, adductor arcuum branchialium ; 

 C, constrictor arcuum branchial ium ; ('pli, portion of the constrictor of the 

 pharynx arising from the posterior branchial arch ; Dp, depressores branchiarum ; 

 Gh, genio-hyoid : P/i, prouoraco-humeralis ; S//f, supracoracoideus ; Cbb, coraco- 

 brachialis brevis ; Clo, cloaca ; La, liuea alba. 



the latter becoming greatly modified in order to form the walls of 

 the body-cavity. 



I 2 



