84 0. C. Marsh—Principal Charact’rs of Coryphodontide. 
The manus and pes of Coryphodon had each five short digits. 
The carpal bones are shorter, measured in the line of the foot, 
than in Dinoceras, and the distal row present more curved 
articular faces to the metacarpal bones, indicating greater free- 
om of motion. The pyramidal is destitute of the tubercle 
projecting outward and forward for the support of the fifth 
digit, seen in Dinoceras. The metapodial bones and phalanges 
are throughout less roughened and tubercular than in Dinoceras, 
and all their articular faces indicate greater flexibility in the 
feet. The ungual phalanges expand laterally for the support 
of the hoofs, instead of being rounded, as in Dinoceras. ; 
In the hind foot, the astragalus, and in a less degree the 
cuboid and navicular bones are shorter, along the line of the 
foot, than the corresponding bones of Dinoceras. The astragalus 
has the tibial articulation less convex, and the fibular articula- 
tion more extensive, covering the whole exterior or fibular side 
of the bone. The navicular and cuboid faces are more dis- 
tinctly separated, and make a greater angle with each other 
than in Dinoceras. The caleaneum approaches the ordinary 
perissodactyl type, the shaft being much longer than in Dino- 
ceras, and the tubercular surface below for the support of a 
plantar pad, seen in the Elephant and Dinoceras, is undeveloped. 
The cuboid is of peculiar shape, being sub-triangular. he 
caleaneal face is long and oblique, reaching nearly to the face 
for the fifth metatarsal. Both the metatarsal articulations are 
essentially in one plane, and are separated only by a very slight 
ridge. The navicular articulates very slightly, if at all, with the 
cuboid, but covers the face of the astragalus, and fully supports 
the ectocuneiform. The latter bone is not at all supported by 
the astragalus, as asserted by Cope (Catalogue of Vertebrata of 
the Eocene of New Mexico, p. 27). He has also published a 
remarkable figure of the hind foot of Coryphodon (Bathmodon), 
showing the hallux with three phalanges, and the fifth digit 
reduced to a rudiment (loc. cit., p. 28 
The average size of the animals of this genus was about that 
of the existing Tapir. Some were smaller, and others nearly 
twice as large. Their mode of life was probably similar. 
A careful consideration of the characters of Coryphodon, so 
far as now known, indicates that the genus represents a distinct 
family of perissodacty] Ungulates, the Coryphodontide. The 
skull is clearly of this type, and the skeleton and feet present 
no differences sufficiently important to justify a separation from 
that natural order. Only a slight modification of the limits of 
the Pertssodactyla, would bring this five-toed genus into it, and 
simplify classification. 
he geological horizon of Coryphodon in this country is near 
the base of the Eocene, in the strata named by the Survey of 
