In the horse the ribs increase in length from the first to the ninth; they are flattened from without inwards, and increase in width from the first to the sixth or seventh, and the following ones become narrower. The costal cartilages, from the second to the eighth, are, as in the ox, at first flattened laterally, near the ribs; while near the sternum they are flattened from front to back.
In birds, the ribs are each furnished with a flat process ([Fig. 18], 10), which springs from the posterior border, is directed backwards, and overlaps the external surface of the succeeding rib. These processes are not found, as a rule, on the first or last ribs.
As for the costal cartilages, they are, as a rule, ossified, and receive the name of inferior ribs ([Fig. 18], 11), united to the preceding (superior ribs; [Fig. 18], 9) by articulation; by the other extremity they are joined to the sternum; the first superior ribs generally want them. Sometimes the last inferior rib becomes connected with the one that precedes it, not articulating with the sternum; and thus recalls the relations of the asternal ribs which we have noticed in our study of the mammals.
In the bat, as in birds, the costal cartilages are ossified.
THE ANTERIOR LIMBS[5]
[5] Consult [Figs. 21], [33], [34], [38], [39], [46].
The anterior limbs, homologous to the upper limbs in man, are formed, as in the latter, of four segments: the shoulder, the arm, the forearm, and the hand. These limbs, considered in the vertebral series, present themselves under very different aspects, which are determined by the functions they are called upon to perform.
