98 OUTLINES OF EQUINE ANATOMY. 



tlie corresponding bones of the fore, thongli each presents 

 certain points of difference which will be noticed. 



OS METATARSI MAGNUM differs from the large meta- 

 carpal hone. — In being about one and one-third times as 

 long, in being rounder, in having the articular surfaces for 

 the splint bones more posteriorly placed. In a tendency 

 to the production of a sharp ridge running from the upper 

 surface of the bone downwards over the central line of 

 of the antero-superior part. In the arrangements of its 

 upper surface, which presents two distinct articulatory 

 surfaces, one anteriorly crescent-shaped, one posteriorly 

 placed rounded. These are separated by a roughened 

 groove. Supero-externally is a groove running obliquely 

 downwards and backwards for the metatarsal artery. 



OS METATARSI PARVUM EXTERNUM is much the 

 largest of the four splint bones. Its upper extremity 

 presents at the antero-external part a facet for os cuboides, 

 but the rest of this extremity which is rough and tuberous 

 as well as its size renders it readily distinguishable. 



OS METATARSI PARVUM INTERNUM is distin- 

 guishable by its upper extremity, which has two articu- 

 latory facets (continuous with that for union with os 

 metatarsi magnum) for os cuneif orme parvum, and one on 

 its outer side for cuneiforme medium. These facets with 

 the rest of the surface which is rough, render the extreme 

 upper part somewhat pointed. 



OS SUFFRAGINIS is larger at its superior extremity, 

 smaller at its inferior than that of the fore limb. 



OSSA SESAMOIDEA, OS CORON-ffi present no marked 

 difference ; OS NAVICULARE is smaller. 



OS PEDIS may be distinguished: — By the slight ob- 

 liquity of its antero-lateral surface ; by the greater con- 

 cavity, less circular, more regularly semilunar shape of 

 its plantar surface, which is widest at the toe and gradually 

 decreases in size towards the heels, while that of the fore 

 limb present an indentation into the central part of its 

 posterior crescentic margin. 



