1004 The Perissodactyla. [Nov, 
from Loup 1 
] size; 
Peraceras superciliosus Cope, about Ee natura 
FIG. 18. 
Fork bed of Nebraska. Original. Fig. a, left side; 4, from below. 
A. Four anterior digits. s ak 
therium 
Incisors f; canine {; no horn; posttympanic bone distinct Acera: 
AA. Three anterior digits 
a. Posttympanic process n not coossified with postglenoid. 
l 
Japs Cope 
Incisors 4; canines 2; no der RE EE EE A eae 
Incisors $; canines $; no dermal horn; ........sesseseere seseeeee 
Incisors 4; canines fia tuberosity for a dermal thickening on 4 Marsh. 
each nasal bone ; websesedsuses herin 
Gray. 
‘Incisors 4; canines 9; a median dermal nasal horn; PEET A eS | 
Incisors $; canines $; dermal horn median ; no osseous nasal Atelodus Pomel. 
aa, Posttympanic process coossified with postglenoid; 
B. No median frontal horn-core. 
Incisors }; canines $; ni horn median; nasal septum erus Linn. 
Aam n 
