THE ENDOSKELETON 



139 



nite in shape and irregular in occurrence, as is usually found 

 in an organ at its beginning, before the type has become fixed. 



d 



in 



c 



FIG. 36. Morphology of the sternum. 



(a) Necturus (a primitive salamander), (b) A higher salamander, (c) Frog, 

 (d) Lacerta (European lizard), (e) Cat. 



c, coracoid; d, epicoracoid; e, episternum; f, clavicle; g, scapula; h, suprascapula, 

 p, procoracoid; st, sternum; m, manubrium; stb, sternebrae; x, xiphisternum. 



If we seek the reason for their appearance we shall probably 

 find it in an attempt to lessen the pressure upon an important 



