376 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Genus PANOLAX Cope. 
Panolax Corr, Proc. Acad. Nat. Sci. Phila., 1874, 151. 
‘“‘Molars prismatic, transverse, except the first and last, each divided by 
a plate of enamel extending transversely from the inner side. Anterior molar 
longitudinal; posterior molar composed of two columns. 
“This genus is represented by numerous teeth and portions of the 
cranium. It evidently belonged to the Leporide, and is allied both to Lepus 
and Paleolagus. As the teeth are mostly separate, it is not easy to determine 
which is the posterior and which the anterior molar. Judging by the analogy 
of the known species, the determination as here made is correct. Should the 
relations be reversed, the species will be referred to Pal@olagus.” —( Cope, |. ¢.) 
From the nature of the materials, the character of this genus cannot well 
be determined. Its admission here is of course provisional only. 
PANOLAX SANCT-FIDEI Cope. 
Panolax sancie-fidei CoP, Proc. Acad. Nat. Sci. Phila., 1874, 151. 
This species is known only from several detached molar teeth, found in 
the Santa Fé marls. These marls have been regarded by Dr. Hayden as of 
late Tertiary age, and are found, according to Professor Cope, to contain the 
remains of numerous Pliocene genera, which show the fauna to be a part 
of that described by Dr. Leidy and Professor Cope as occurring in the 
Pliocene deposits of Colorado and Dakota. 
. In this species, the (supposed) first molar is deseribed as having the 
triturating surface twice as long as broad, with an entering loop of enamel on 
the inner side; the last molar as being as wide antero-posteriorly as trans- 
versely, the shaft curved backward, the posterior column subcylindric, half 
the diameter of the anterior. This species Professor Cope supposes to have 
been of about the size of the Northern Hare (Lepus americanus), and hence 
considerably larger than Paleolagus haydeni, which is described by Dr. Leidy 
as being somewhat smaller than Lepus sylvaticus. 
Genus PRAOTHERIUM Cope. 
Praotheritum Corr, Proc. Amer. Phil. Soc., xii, 1871, 93. 
“Molars similar to those of Lepus, rootless, with oval crowns transverse 
to the axis of the series, all simple ; masti catory surface not divided by median 
Oe 
