1883.] The Extinct Rodentia of North America, 173 
Hayden who discovered it. It was an ex- 
tremely abundant species, and no doubt fur- 
nished much food for the Carnivora of the 
Lower Miocene period. There are two other 
species found in the same horizon, the P. tur- 
gidus Cope (Fig. 20), and P. triplex Cope, both 
larger than the P. haydeni. The former is as 
large as the northern hare, Lepus glacialis, and 
had the teeth much like those of the P. tay- 
deni, The P. triplex is of similar dimensions, 
and has the third column to the permanent @ 
molars which characterize the immature stage _ = 
Fic. 20.—Pa/leolagus 
of the other species. haydeni Leidy, tempo- 
A species of the size and appearance of the at Sig wren, P ety 
P. haydeni is found in the John Day beds of 2 two temporary and 
one permanent tie 
Oregon, and a similar one occurs in the Loup molars; tw 
Fork beds of New Mexico. As nothing but POY inferior molar 
teeth of these animals are known, nothing can sage ene molars 
yet be finally determined as to their specific F From ae ees ea 
affinities, l ot s of Colorado. Orig- 
: inal. 
PanoLax Cope. 
In this genus the last 
Superior molar consists of 
two columns; otherwise 
the superior teeth are as in 
the last genus. The single 
Species known, FPanolax 
Sanctefidei Cope, was as 
large as the northern hare. 
Itis found in the Loup Fork 
formation of New Mexico. 
Lepus Linn. 
„_ Dental formula: I.}; C. 
03 P-m.§ CM 3 First pe 
parior. cnt sani, first 
inferior molar with two ex- 
ternal grooves ; last inferior 
molars consisting of two Fic —Lepus ennisianus Cope; cra 
cylinders. Postorbital pro- Nat sae Trond the To, Day Eo ren 
cesses ginal. From the U., S. ata 1 Survey 
Present. Toes FY. ‘Hayden, Vol. 1v. 
