170 
ridges. In £. 
PaL@®oxacus Leidy. 
With this genus we enter the Lagomorpha, or rabbits, and theit 
19.—Palzolagus prae Leidy, 
rest size, from ss White — beds of 
Colorado, a anter rt of cranium from 
below; 4 mandi ble poe pet c do. 
from external side; d tibia; e distal end 
of do. from below. igi äl 
external side in the known species. 
The Extinct Rodentia of North America, [Feb 
. minor and E. planifrons (Fig. 18), the frontal bone 
is flat, and Æ. minor is smaller than the other species. 
hae 
a 
allies. It is probable that rabbits 
were as numerous in species in 
Miocene times in North Ami 
ca as they are at present, butthè : 
number of extinct species yet 
known is smaller than the recent : 
The characters of Palzole 
approximate nearly those of he A 
existing genus Lepus. The only 
distinction between them signal: | 
ized by Dr. Leidy, is the mabye. 
simple first inferior molar of the 
extinct genus, which aai 
one column more or less divided. 
In Lepus this tooth consists 
two columns, the anterior of 
which is grooved again on © 
I am able to reinforce 
distinction by a strong character, viz., the absence of the po% 
frontal process in Palzolagus 
genus Titanomys of Meyer, the difference is well marked, Se 
that genus has the molar teeth 4 
molar is cylindric, consisting of Hü one siini. 
rior molar consists of two cylinders broadly united, as in 
responding tooth of Palzolagus. be 
Cope,’ which is only known from superior molar teeth, this gem 
may be at once recognized by the simplicity of ji last tooth. i 
Panolax it consists of two columns. (See Fig. 19.) 
Dr. Leidy’s descriptions and figures, Köik a are aisit 
definition of this genus, relate exclusively to the dentition. 
acters drawn from the skeleton give some available indi 
The condyles of the humerus are more primitive than je 
the species of Lepus, in having a less developed intertré 
crest. The tibiotarsal, or ankle joint, is, on the other 
1 Amphilagus. Catal. Méth. et Deser. Vertebés Fossiles de la Bassin de 
3853, P- 42. 
? Report Lieut. G. M. Wheeler, 4to, 1v, p. 296. 
As compared with the € 
instead of Ê. 
As compared with 
band 
