1898.] Wortman, Extinct Caiiic/idce of North America. 1 05 



anterior root of the zygomatic arch, while upon the left side the 

 greater part of the orbit is missing. Fortunately the skull 

 contains the dentition nearly complete. In association with it 

 were found the greater part of an ulna and radius of the same 

 individual. A second specimen which I refer to this genus and 

 species includes a large part of both hind legs, together with a 

 large number of vertebrae, ribs and other parts of the skeleton. A 



Fig. 3. Side view of slcull o{ Protylopus petersoni. 



third specimen contains hind limbs and vertebra, while a fourth 

 includes the greater part of a hind foot. 



The more important generic characters may be stated as 

 follows : 



Molars tetraselenodont without intermediate cusps. Teeth of the typical 

 number, forty-four, arranged in a continuous series. Canines of both upper 

 and lower jaws small and incisiform, the first inferior premolar not caniniform. 

 The first three superior premolars elongated from before backwards, secant and 

 without accessory cusps, the fourth with single external and internal crescentic 

 cusps. The inferior premolars elongated and cutting, the fourth without 

 internal cusps. Hind feet provided with but two functional digits, the outer 

 ones, second and fifth, reduced to mere vestiges. Lumbar vertebral formula 7. 

 Ulna and radius, at least in old individuals, coossified in the middle part of 

 their shafts but free at their proximal ends. 



The skull is crushed laterally so as not to reveal the exact form 

 of the face, but it can be safely stated that the muzzle had 



