12 AiXATOiMY OF THE HORSE. 



Peculiarities. The ftrst is the shortest and tliickest of the 

 ribs ; its upper part is rounder, and its lower broader and more 

 expanded than any other : it is but httle and irregularly arch- 

 ed, and the concavity of its arch is turned directly forwards. 

 The second is a remarkably straight rib, being only curved in 

 its neck. From the second the ribs progressively increase iix 

 breadth to the seventh, in length to the ninth, and in curvature 

 to the very last ; the eighteenth being in proportion to its length 

 the most crooked rib : from the tenth, the ribs grow shorter, 

 narrower, and more obtuse or rounder in their borders. The 

 posterior differ also from the anterior ribs in being curved 

 throughout their entire length ; whereas the former are only 

 very perceptibly bent at their angles. In the eighteenth, and 

 sometimes in the seventeenth rib, the articulatory surface of 

 the tubercle is confounded with that of the head, and the 

 neck is wanting. 



The Cartilages of the Ribs, properly so called in the 

 young subject, receive depositions of osseous matter as the animal 

 advances in life, until at length they acquire rather the charac- 

 ter of spongy fragile bones than cartilage. They correspond in 

 number to the ribs, and like them increase in length from the 

 first to the ninth or tenth, after which they progressively de- 

 crease ; but this is liable to variation: the first cartilage is re- 

 markably short; those belonging to the true ribs are in 

 general not very long, but broad, thick, and resisting; those 

 proceeding from the false ribs are on the contrary mostly very 

 long and comparatively slender, and incapable of offering much 

 resistance — are in fact so formed and connected that they admit 

 of considerable motion. 



lllE BREAST-BONE. (STERNUM.) 



Conjonnation. The sternum (being a single bone) is symme- 

 trical in its form, shaped, altogether, like the keel of a ship ; 

 posteriorly, flattened from above downwards; anteriorly, from 

 side to side. It is composed of seven irregularly formed bones, 

 and of the ensiform and cariniform cartilages. 



Division. Into four surfaces and two extremities. 



TAe Superior and Inferior Surfaces are pyramidal in figure, 

 being broad posteriorly, contracted into borders anteriorly : the 

 former, slightly concave, terminates between the cartilages of 

 the two first ribs ; the latter, irregularly convex, ends in the ca- 

 riniform cartilage. 



The Lateral 'Surfaces are broader anteriorly than posteriorly. 

 The three foremost bones present broad, superficial, lateral con- 



