FOSSIL LErOEID^E— PKAOTIIEIUUM. 377 



ridge; enamel-boundary cmarginate on the inner side. Number of molars in 

 maxillary bone 1 ? 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 Cor*:, Proc. Amer. Phil. Soc, xii, 1871, 94, fig. 20. 



This species 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 L. 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 Palceolagus liaydeni. 



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 



