288 PROFESSOR SCOTT ON POEBROTHERIUM CHAP. 
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 Poebrothervum. 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. 11, 17, 1°, Incisors 1-3. 
(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-ossitied 
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. 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 toa Lama. It is an important fact to notice that at this 
1 “Osteology of Poebrotherium,” Journ. Morph. v. 1891, p. 1. 
