OSTEOLOGY. 77 



surface presents an articulately convexity extending obli- 

 quely downwards, outwards, and backwards. The outer 

 part of this articulates with cuneiforme, the inner with 

 lunare and extends to a superior facet on the inner surface 

 for articulation with magnum. The inferior s?M/ace presents 

 three articular parts, the anterior, extending obliquely 

 outwards and backwards, internally continuous with the 

 inferior facet for magnum on the internal surface. It 

 articulates with metacarpi magnum, as also does the 

 posterior part, which slightly meets the former by its 

 anterior angle, but is separated from it inwardly by an 

 indentation on its inner margin, externally by the middle 

 part of the surface, which articulates with the outer small 

 metacarpal bone. This surface presents a semicircular 

 figure, and a groove extends round its outer margin. The 

 in7ier surface so exactly corresponds with the outer surface 

 of OS magnum that one description will suffice for both. 

 The posterior facet is on the inner side of the process, the 

 outer, posterior, and superior parts of which are rough, as 

 also is the anterior surface, affording attachment to the 

 annular ligaments, bounded on every side by grooves 

 mapping out the articulatory facets of the neighbouring 

 surfaces. 



OS PISIFORME is a small osseous nodule found on the 

 inner side of the lower row, articulating with trapezoides, 

 and the inner small metacarpal bone, for which it presents 

 small articulatory facets. Its presence is by no means 

 constant ; it is relatively larger in the ass than in the 

 horse. 



THE METACARPUS 



is formed of three bones, the largest of which is centrally 

 placed, with a smaller one on each side of it. It extends 

 from the knee to the fetlock, but the small bones only 

 proceed downwards part of this distance. 



OS METACARPI MAGNUM (CANON OR SHANK 

 BONE) is a long, round bone, extending from the knee to 

 the fetlock, having two extremities and a shaft. The 

 shaft is flattened from behind forwards, and presents two 

 surfaces connected by Iwo rounded margins. The anterior 

 surface extends in a straight line from above downwards, 

 is convex and rounded from side to side, becoming flat- 

 tened, and li^.ore expanded superiorly and inferiorly. It is 



