THE SKELETON OF THE NEWT. ANTERIOR LIMB. 147 



The precoracoid (fig. 22, 5) forms a small forwardly- 

 directed cartilaginous plate. The coracoid (fig. 22, 3) forms 

 a much larger plate, the greater part of which is unossified 

 and overlaps its fellow in the middle line, the two being over- 

 lapped by the sternum. Around the glenoid cavity is an area 

 which is mainly ossified and is continuous with the scapula. 



B. THE ANTERIOR LIMB. 



This is divisible into three parts, the upper arm or 

 brachium, the fore-arm or antibrachium, and the maims. 



The upper arm includes a single bone, the humerus. 



The humerus is a slender bone cylindrical in the middle 

 and expanded at either end, the proximal part forms a 

 rounded head which articulates with the glenoid cavity. 

 Along the proximal part of the anterior or pre-axial surface 

 runs a strong deltoid ridge. The proximal part of the post- 

 axial surface also bears a small outgrowth. 



The fore-arm contains two bones, the radius and ulna, both 

 of which are small and imperfectly ossified at their terminations. 



The radius (fig. 23, B, 11) or pre-axial bone is rather 

 the larger of the two, and is considerably expanded at its 

 proximal end. The ulna or post axial bone is somewhat 

 expanded distally, but is not drawn out proximally into an 

 olecranon process. 



The manus consists of two parts, a group of small bones 

 forming the carpus or wrist, and the hand. 



The carpus is in a very simple unmodified condition as 

 compared with that of the Frog. It consists of a proximal 

 row of two bones and a distal row of four, with one, the 

 centrale, interposed between. All these bones are small and 

 polygonal and are imbedded in a plate of cartilage. 



The bones of the proximal row are a smaller pre-axial bone, 

 the radiale (fig. 23, B, 13), and a larger postaxial bone, which 

 represents the fused ulnare and intermedium of the very 

 simple carpus described on pp. 26 and 27. 



102 



