FOSSIL LEPORID#—PRAOTHERIUM. Shed 
ridge; enamel-boundary emarginate on the inner side. Number of molars in 
maxillary bone? four.”—( Cope.) 
This genus, according to Professor Cope, differs from Lepus and Lagomys 
in {he absence of an enamel band dividing the triturating surface of each 
molar, though a trace of the dividing lamina is sometimes visible, but does 
not appear to ever form a transverse median crest. The normal number of 
teeth is uncertain, but supposed to be only four on each side of the upper 
jaw. Only one species has thus far been described, from remains found in 
the Port Kennedy bone-cave, Chester County, Pennsylvania, associated with 
those of a great variety of extinct species, mingled with a few of species still 
existing. The genus is known from the single species— 
PRAOTHERIUM PALATINUM Cope. 
Praotherium palatinum Corr, Proc. Amer. Phil. Soe., xii, 1871, 94, fig. 20. 
_ This speeies was described by Professor Cope from the palatal portion 
of a skull, containing four molar teeth on each side in position, found in the 
Port Kennedy bone-cave. It differs, says Professor Cope, from the Ameri- 
can species of Lepus in its small size, and in having the molars deeply grooved 
longitudinally on the inner instead of on the outer side.‘ In worn teeth, this 
groove is continued into the grinding surface of the crown, without interrup- 
tion from the inclosing enamel. The form of this surface is then an oval, 
notched on the inner side, and rounded or slightly truncated on the outer, 
The palatine face is but partially preserved, and is considerably wider in pro- 
portion to the diameter of the teeth than in Lepus sylvaticus.” In Lepus 
callotis, however, there is a deep longitudinal groove on the outer side of 
the tooth, and none on the inner; while, in LZ. californicus, there is quite a 
distinct groove on both sides. The prominence, or even presence, of the 
median transverse ridge varies with age in the living species, as Dr. Leidy 
has shown it to do in specimens of Paleolagus haydeni. 
FOSSIL REMAINS OF EXISTING SPECIES. 
In addition to the above described extinct species of Hares, the remains 
of several of the existing species have been met with in different bone-caves 
and elsewhere, sometimes associated with the remains of a variety of other 
extinct species of Mammalia. Dr. Leidy has recorded the occurrence of the 
fossil remains of Lepus sylvaticus in the crevices of the lead-bearing rocks of 
] A 5 
