870 THE WHITE EIVEE FAUNA. 



nects the occipital condyle and the paroccipital process, c^ove which is the 



condyloid foramen. 



Measurements. 



M. 



Length from middle of supraorbital border to inion 018 



Width of interorbital space 0055 



Width between mastoid bulliB 0190 



Width of occipital bone 0100 



Width of foramen magnum 0050 



Length of otic bulla alone 0100 



This cranium is well preserved, and has been perfectly cleaned by 

 weathering. It shows a good many points of difference, as compared with 

 any of the other species of this group. It is to be regretted that the teeth 

 are wanting. 



LAGOMORPHA. 

 PAL^OLAGUS Leidy. 



Proceedings Academy Philada., 1856, p. 89; Extinct Mamm. Dakota and Nebraska, p. 33L — Cope, 

 Ann. Report U. S. Geol. Surv. Terrs., 1873 (1874), p. 477. 



2 6 3 3 



Family Leporidce. Dentition : I. ; C. -^ ; M. - ; or, Pm. - , M. -. 



Superior incisors sulcate, inferior incisors not sulcate. First and last supe- 

 rior molars simple, intermediate ones with an enamel inflection of the inner 

 side, which soon wears out First inferior molar of one more or less trans- 

 versely divided column; other inferior molars consisting of two columns in 

 antero-posterior relation. No postfrontal process. 



The above characters approximate nearly those of the existing genus 

 Lepus. The only distinction between them signalized by Dr. Leidy is the 

 more simple first inferior molar of the extinct genus, which consists of one 

 column more or less divided. In Lepus this tooth consists of two columns, 

 the anterior of which is grooved again on the external side in the known 

 species. I am able to reinforce this distinction by a strong character, viz, 

 the absence of the postfrontal process in Palceolaffus. As compared with the 

 extinct genus Titanomys of Meyer,^ the difference is well marked, as that 

 genus has the molar teeth f instead of |. The last inferior molar is cylin- 



' Amphilagua. Catal. M^th. et Descr. Vertfebres Fosslles de la Basin de la Loire, 1853, p. 42. 



