The bones of the forearm (fig. 316., A. 2, 3) are intimately united, and, being connected to the humerus by a simple hinge joint, are always retained in a state of pronation — as the surface corresponding to the palm of the hand is always directed backwards ; to increase the steadiness and strength of the limb, the upper end of the ulna is very thick, and in the upright position of the animal the articular angle of the olecranon is firmly locked between the brachial condyles. There is a deep groove indicating the radio-ulnar line of union, at the upper part of which is a vacant space, and another is sometimes present near the distal end. In certain individuals the ulna is represented by two distinct pieces, the central part of the shaft having disap peared. In all cases the olecranon is ex tremely prominent, and the bone is relatively much longer than the radius. There is no vacant interval between the bones in the Caniel, which together acquire an extra ordinary length. The radius and ulna in the Javanese musk are nearly of equal bulk, and the line of attachment is very distinct through out. In a specimen preserved in the Edin burgh College of Surgeons' Museum, the bones of the right side are anchylosed only at the middle of the shaft.
All ruminants possess six carpal bones (A.A. 316.), and some have seven, which are disposed in two rows. In the upper may be recognised the os scaphoides (4), os lunare (5), os cuneztorme (6), and os piszfbrme (7); in the lower the os trapezoides (8) and os magnum (9), and in the Giraffe and Camel the os und forme (c, a.).
The metacarpals are represented by a central cannon bone (10), and in the Deer tribe and Antelopes by two additional rudi mentary splint-like pieces, which are separated from the lower and back part of the former by the intercalation of four ossa sessamoidea.
The large central shaft or cannon is in reality composed of two metacarpals, as can be readily demonstrated by making a longi tudinal section, such as is displayed in the annexed woodcut (fig. 347.). In this view the duplicity of the shaft is shown by the thin lamina of compact osseous tissue (d), traversing the hollow cylinder from end to end ; and its duality is further evinced by the bifid character of the distal extremity (a, b), as well as by a deep median furrow at the posterior surface. The two splint bones are homologous with the metacarpals of the index and little fingers in the human subject. They are not present in all ruminants ; but in the Deer they attain a considerable size, and support two small digits. In some cervine species these styliform metacarpals are seen attached at both extremities of the cannon bone. In the genus Moschus they are as long as the shank, forming thus a transition to wards the fotub-toed pachydermata.
Six phalanges enter into the composition of the cloven foot, the two upper being the longest, and having a position analogous to the pastern bone of Solipeda; the superior arti cular surfaces are deeply grooved for the re ception of' corresponding ridges (fig. 317. c, c),
surmounting the trochlear facets of the can non bone. The second pair are short, the distal end presenting an extended convex plane for the hinge movement of the ulti mate phalanx. A sasamoid bone is some times seen behind this joint. The last pair are more or less triangular, and their com bined plantar surfaces form a semicircular disc, resembling that of the coffin bone of the Horse. In those genera which have super numerary digits, the rudimentary phalanges do not, under ordinary circumstances, reach the ground; and though invested with a hoof like covering, they can but slightly aid in supporting the weight of the body. In the Rein-deer, however, as Sir Charles Bell ob serves* " these bones are strong and deep, and the toe, by projecting backward, extends the foot horizontally, thus giving the animal a broader base to stand on, and adapting it to the snows of Lapland, on the principle of the snow-shoe." The same observation ap plies, though in a more limited sense, to those species where the lateral toes are less conspicuously developed, in which case the elasticity and firmness of the spring will be heightened when bounding through weedy thickets and on grassy moors.
Bones of the posterior extremity. — The bind and fore limbs are not of equal length, and if the actual extent of the individual bones be added together, the balance will be found in favor of the posterior limb. This is evident at a glance in the genus Moschus, and in the Giraffe there is no ex ception to this rule. In order to make our position clear, the following relative ad measurements are deciphered from personal exammation : — It will be remarked that the proportionate difference, as here indicated, is much less in the Arabian camel than in the more typical ruminants.
'The femur (fig. 346. B. 1) resembles for the most part that of other mammifera, being characterised by a rather short shaft and neck, and having the head placed nearly in a line with the longitudinal axis. The great trochanter is prominent, and forms the highest point when the limb is placed in an upright position. The inter-trochanteric fossa is capacious. The bone presents at the inferior end an extended articular surface, and bulges at the forepart, where it is deeply grooved for the patella and tendon of the quadratus muscle. Behind the external condyle is a hol low, and its rough outer margin is continuous with the faintly indicated linea aspera. In the Giraffe the distal extremity of the thigh bone attains a prodigious development. The nutritious artery enters at the anterior aspect of the cylinder a little below the cervix, as in other keratopherous ruminants ; we have also observed the arterial foramen of the left side to be about half an inch lower than on the right, an arrangement analogous to the devia tion noticed in connection with the hutnerus of this species.