37G MONOGRAPHS OF NORTH AMEEICAH RODKNTIA. 



Genus PANOLAX Cope. 



Panolax Cope, Proo. 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 Lepor'u/ce, and is allied both to Lepus 

 and Ptrftfolagus. 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 Pa/ceolagus.''' — (Cope, 1. c.) 



From the nature of the materials, the character of this genus cannot well 

 be determined. Its admission here is of course provisional only. 



PANOLAX SANCTtE-FIDEI Cope. 



Panolax sanctwfalei Cope, Proc. Aca<l. Nat. Sci. Phila., 1874, 1 51. 



This species is known only from several detached molar teeth, found in 

 the Santa Fe 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 apart 

 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 described 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 Palaohtgus haydeni, which is described by Dr. Leidy 

 as being somewhat smaller than Lepus sylvaticus. 



Genus PRAOTHERIUM Cope. 



Praothertam Cope, Proc. Amor. Phil. Soo., xii, 1871, 93. 



''Molars similar to those of Lepus, rootless, with oval crowns transverse 

 to the axis of the series, all simple; masticatory surface not divided by median 



