FOSSIL MAMMALS. OF THE ORDER DINOCERATA. 149 
approximate, and their summits are obtuse and nearly round. 
(Plates I, II.) Below these horns are the huge decurved canines, 
the extremity of the fang being implanted in the base of the horn- 
core. Behind the canine, there is a moderate diastema, followed 
by six small premolar and molar teeth. The crowns of the molars 
are formed of two transverse ridges, separated externally, and 
meeting at their inner extremities. The nasals are massive, and 
greatly prolonged anteriorly. In front of the zygomatic arch they 
contract, and form the inner inferior surface of the maxillary horn- 
cores, as well as an elevation between them. From this point for- 
ward to the anterior margin of the suture with the premaxillary, 
they increase slightly in width, and then contract to the end of 
the muzzle. 
Near the anterior extremity of the nasals, there is a pair of low 
tubercles, which evidently supported dermal horns (Pl. II, fig. 3). 
The premaxillaries are without teeth, and quite peculiar. They 
unite posteriorly with the mavxillaries just in front of the canine, 
and then divide, sending forward two branches, which partially 
enclose above and below the lateral portion of the narial opening. 
The upper branch is closely united with the adjoining nasal, thus 
materially strengthening the support of the nasal horns. The 
lower portion is slender, and resembles the premaxillary of some 
Ruminants. The extremity is somewhat behind that of the nasals, 
The anterior. nares are comparatively small, the aperture being 
more contracted than ‘in the rhinoceros. The lower jaw was 
slender, and the tusks small. 
he extremities in the Dinocerata resembled those in the 
Proboscidea, but were proportionally shorter. The humerus was 
Short and Massive, and in its main features much like that of 
the elephant. One of the most marked differences is seen in the 
great tuberosity, which does not rise above the head, and is but | 
little compressed. The condylar ridge, moreover, of the distal 
end is tubercular, and not continued upward on the shaft. The 
lower extremity of the humerus is much like that of-the rhinoc- 
_ €ros, and the proportions of the two bones are essentially the 
‘Same. The head of the radius rests on the middle of the ulnar os 
articulation, and hence the shaft of this bone does not cross that 
of the ulna so obliquely as in the elephant. The femur is pro- _ 
. Portionally about one-third shorter than that of the elephant. The — 
_ head of this bone has no pit for the round ligament, and the great 
trochanter is fattened and recurved. There is no indication of a 
