OSTEOLOGY AND ARTHROLOGY 63 



at the internal aspect ; but, when present, it is but very 

 shghtly developed. 



The principal metacarpal consists of two metacarpals 

 fused together ; on this account the bone is longitudinally 

 marked in the median line by a slight depression which 

 marks the junction of the two bones of which it is 

 formed. In some ruminants (certain species of chevrotains) 

 the coalescence does not take place, and the two meta- 

 carpals remain separate. 



The anterior surface of the principal metacarpal is convex 

 transversely; its posterior surface is flattened. The superior 

 extremity of this bone articulates by two facets with the 

 two bones of the inferior row of the carpus ; on the internal 

 part of the anterior surface of this extremity is found a 

 tubercle. The inferior extremity is divided into two parts 

 by a fissure or notch ; each part is articular, and consists 

 of two separate condyles, which are separated from each 

 other by an antero-posterior crest ; on each side of this 

 crest, and behind, are found two sesamoid bones. As for 

 the external rudimentary metacarpal bone, it is nothing 

 more than a small, short tongue of bone ; which, in goats 

 and sheep, is often absent. 



The division of the inferior extremity of the principal 

 metacarpal into two parts is correlated with the two perfect 

 digits which give the foot of the ruminant its forked appear- 

 ance. Each digit consists of three phalanges, which are 

 directed obliquely downwards and forwards ; further, these 

 phalanges are inclined a little outwards from the axis of 

 the limb, so that the two digits diverge from each other as 

 they descend. 



The first phalanx, which is the longest, articulates 

 superiorly with the principal metacarpal ; its inferior 

 extremity terminates in a trochlea, and the lip of this, 

 which is situated towards the axis of the limb, descends 

 lower than that of the opposite side ; this arrangement is 

 correlated with the divergent direction of the digits. The 

 second phalanx has its superior extremity moulded on the 

 trochlea which terminates the extremity of the first ; its 

 inferior extremity is articular, and elongated from before 



