302 UNGULATA 
is long and slender; the suprascapular border is rounded, and 
slowly and imperfectly ossified. The spine is very slightly devel- 
oped ; rather above the middle its edge is thickened and somewhat 
turned backwards, but it gradually subsides at the lower extremity 
without forming any acromial process. The coracoid process is a 
prominent rounded nodule. The humerus is stout and rather 
short, and has a double bicipital groove. The ulna is quite rudi- 
mentary, being only represented by little more than the olecranon. 
The shaft gradually tapers below, and is firmly ankylosed to the 
radius, The latter bone is of nearly equal width throughout. The 
three bones of the first row of the carpus (the scaphoid, lunar, and 
cuneiform) are subequal in size. The second row consists of a very 
broad and flat magnum, supporting the great third metacarpal, 
having to its radial side the trapezoid, and to its ulnar side the unci- 
form, which are both small, and articulate distally with the rudi- 
mentary second and fourth metacarpals. The pisiform is large and 
prominent, flattened, and curved ; articulating partly with the 
cuneiform and partly with the lower end of the radius. The large 
metacarpal is called in veterinary anatomy “cannon-bone”; the 
small lateral metacarpals, which gradually taper towards their 
lower extremities, and lie in close contact with the large one, are 
called “ splint-bones.” The single digit consists of a moderate-sized 
proximal (0s suffraginis, or large pastern), a very short middle (os 
corone, or small pastern), and a wide, semi-lunar, ungual phalanx 
(os pedis, or coffin-bone). There is a pair of large nodular sesamoids 
behind the metacarpo-phalangeal articulation, and a single large 
transversely extended sesamoid behind the joint between the 
second and third phalanx, called the “ navicular bone.” 1 
The carpal joint, corresponding to the wrist of man, is commonly 
called the “knee” of the Horse, the joint between the metacarpal 
and the first phalanx the “fetlock,” that between the first and 
second phalanges the “astern,” and that between the second and 
third phalanges the “ coffin-joint.” 
In the hind limb the femur is marked, as in other Perisso- 
dactyles, by the presence of a “third trochanter,” a flattened process, 
curving forwards, arising from the outer side of the bone, about 
one-third of the distance from the upper end. The fibula is reduced 
toa mere styliform rudiment of the upper end; its lower part being 
absent or completely fused with the tibia. The calcaneum has a 
long and compressed calcaneal process, The astragalus has a large 
flat articular surface in front for the navicular, and a very small one 
for the cuboid. The navicular and the external cuneiform bones 
are very broad and flat. The cuboid is small, and the internal and 
middle cuneiform bones are small and united together. The meta- 
podials and phalanges resemble very closely those of the fore limb, 
1 This must not be confounded with the navicular of the tarsus. 
