522 



RUMINANTIA. 



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 

 Camel, 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 

 (k.fig. 346.), and some have seven, which are 

 disposed in two rows. In the upper may be 

 recognised the os scaphoides (4), os lunare (5), 

 os cuneiforme (6), and os pisiforme (7) ; in the 

 lower the os trapezoides (8) and os magnum 

 (9), and in the Giraffe and Camel the os unci- 

 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. 



Fig. 347. 



ection of the cannon lone. (From Lond. Coll. 

 Surg. Museum.) 



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 {Jig. 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, ), 

 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 four-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 (fg.Skl.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 

 hind 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 

 examination : 



* Briclgewater Treatise, "On the Hand," p. 93. 



