70 ELEMENTARY BIOLOGY. [CHAP. 



ft. The great ridge (deltoid crest) on its antero- 

 internal surface, to which a muscle (deltoid) 

 was attached. 



The development of this crest is greater in the 

 male than in the female. 



b. The bone of the forearm. 



a. Excavated above to receive the lower end of 

 the humerus. 



(3. Shewing below two articular heads separated by 

 a notch, which is the last trace of division be- 

 tween the two bones of which it is made up; 

 viz. the radius and the ulna. 



y. Pull the limb out straight, palmar surface down- 

 wards, so that it comes to be situated at right 

 angles to the long axis of the body. The radius 

 and pollex lie on the anterior or pre-axial side, 

 the ulna and little finger on the posterior or 

 post-axial side, of a line drawn through the axis 

 of the whole limb. 



c. The digits. 



Five in number, the first (radial one) rudimentary: 

 beginning at the outer or ulna side, we find 



a. The fifth digit: it presents a cylindrical proximal 

 bone (metacarpal) followed by three others 

 (phalanges), each shorter than its predecessor. 



/3. The fourth digit: a metacarpal bone and three 

 phalanges. 



y. The third digit: a metacarpal bone with two 

 phalanges. 



8. The second digit: a metacarpal bone with two 

 phalanges. 



