7° THE SKELETON OF THE CAT. 
_ Scapholunar Bone. Os scapholunaris (Fig. 51, a).—The 
scapholunar is a quadrangular bone with the ventroradial angle 
produced into a blunt process.. Its proximal surface is smooth 
and articulates with the distal end of the radius. The distal 
end is marked by oblique ridges and articulates with the unci- 
form, os magnum, trapezoid, and trapezium. The ulnar surface 
articulates with the cuneiform, and the dorsal surface of the 
ventroradial process with the radial sesamoid. 
Cuneiform Bone. (Os triguetrum BNA) (Fig. 51, 6).— 
The cuneiform bone has the form of a flattened pyramid. Its 
base articulates with the unciform, its 
proximoulnar surface with the pisiform 
except at its dorsal margin, where it 
articulates with the styloid process of 
the ulna. On its proximoradial sur- 
face is a smooth facet for articulation 
with the scapholunar. 
Pistform Bone. Os pisiforme 
(Fig. 51, c).—The pisiform bone is 
about twice as long as broad, with 
enlarged ends. Its dorsal end articu- 
lates with the cuneiform, and on its 
proximal surface, separated from the 
above by a smooth ridge, is a &mooth 
facet for articulation with the styloid 
process of the ulna. 
Unciform Bone. (Os hamatum 
BNA) (Fig. 51, g).—The unciform is 
a wedge-shaped bone with the apex 
META- 
Fic. 51. — CArpus, 
CARPUS, AND PHALANGES, 
DorsAL SURFACE. 
a, scapholunar bone; 4, 
cuneiform; ¢, pisiform; d@, trape- 
zium; ¢, trapezoid; 7, os mag- 
num; g, unciform; 4%, radia 
sesamoid ; 2, proximal phalanges; 
Jj, second phalanges; 4, distal 
phalanges; I, 2, 3, 4, 5, meta. 
carpals in order from the radial 
side. 
of the wedge directed proximad, and 
smooth for articulation with the 
scapholunar. By a part of its ulnar 
surface it articulates with the cunei- 
form, and by its radial surface with the 
os magnum. Its distal end articulates 
with the fourth and fifth metacarpals. 
Os magnum. (Os capitatum 
BNA) (Fig. 51, f).—The os magnum may be described as an 
