288 



PROFESSOR SCOTT ON POEBROTHERIUM 



and the greater part of a radius and ulna belonging to one 

 individual, and most portions of the hind- limbs in other specimens. 

 The one species, P. petersoni, was about the size of a "jack 

 rabbit," and is late Eocene (Uinta formation) and American in 

 range. The teeth of this mammal are the typical forty-four, and 

 the canines are not pronounced, being incisiform in shape. In 

 the skull the nasals overhang, as in the genus Poebrotherium. The 

 orbit is not closed by bone. There is in this ancient Camel a trace 

 of the supra-orbital notch so characteristic of the Camel tribe. 

 " The vertebrae resemble those of the modern Lamas closely in 

 their general proportions." The lumbars have the usually Cameloid 

 formula of 7. This genus has but two functional toes on the hind- 



FIG. 150. Skull of Poebrotherium wilsoni. I 1 , I 2 , I 3 , Incisors 1-3. x -J-. 

 (After Wortman.) 



feet, the second and fifth being reduced to vestiges. It is interest- 

 ing to note that the radius and ulna appear to remain distinct, 

 except in very old animals, in which they come to be co-ossified 

 in the middle only, thus foreshadowing their complete union in the 

 next genus, Poebrotherium. The present genus, moreover, as well 

 as Poebrotherium, was distinctly unguligrade ; it has not acquired 

 the characteristic phalangigrade mode of progression of the modern 

 types of Camels. 



The American and Oligocene Poebrotherium has been recently 

 and exhaustively studied by Professor Scott. 1 It was considerably 

 smaller than a Lama. Its neck was long as compared with other 

 Artiodactyles, but still shorter than that of the Lama. It was a 

 lightly-built, graceful creature, with apparently some external 

 likeness to a Lama. It is an important fact to notice that at this 

 1 "Osteology of Poclrothcrium," Journ. Morpli. v. 1891, p. 1. 



