Douglass : New Merycoidodonts. 1 01 



men obtained in this locality and horizon, but the beds evidently 

 overlie the Lower White River, which occupies a large area just north 

 of this outcrop. 



The upper molar teeth have nearly the same antero-posterior diam- 

 eter as the corresponding teeth of the type of Oredon {Eucrotaphus ?) 

 major Leidy, 1 but the transverse diameter is a little greater. 



The species is a little larger than the specimen figured as Oreodon 

 major in Leidy' s "Extinct Mammalian Fauna of Dakota and 

 Nebraska" ; all the upper premolar and molar teeth are longer than 

 wide ; the incisors are small ; the molars increasing in length pos- 

 teriorly ; Pj overlapping P T inwardly ; the length of the upper and 

 lower molar series is nearly one and one-fourth times the length of the 

 corresponding premolar series ; the tympanic bullae are inflated, and of 

 medium size ; the paroccipital processes are flattened on the inner 

 surface where they press against the posterior outer portion of the 

 tympanic bullae. They are slender and are directed antero-posteriorly 

 below the bullae, but somewhat twisted on themselves near the ends ; 

 the arrangement of the elements at the posterior base of the skull is 

 nearly as in the species of Promerycochoerus from the Canon Ferry 

 Beds ; the orbits are fairly large, the malar moderately deep ; the pos- 

 terior portion of the zygomatic arch is only moderately heavy ; the 

 sagittal crest is high and thin ; the infraorbital foramen is located over 

 P^ ; the anterior portion of the mandible is low, but increasing in 

 depth backward to the angle which is very large and rounded ; the 

 coronoid processes are low. 



Measurements. 



mm. 

 Length of skull, total 239 



Height of skull 72 



Length of upper premolar series 48.5 



Length of upper molar series 55.5 



Named after the state of Montana. 



Merycoides cursor gen. et sp. nov. 

 (Plate XXIV.) 



(Type No. 1222, Carnegie Museum Catalogue of Vertebrate Fossils.) 



The type, which was collected in 1902 by Earl Douglass in the 



Miocene beds at Canon Ferry, Montana, includes a skull and mandible 



nearly complete, the lower portion of a shoulder blade, part of a 



1 "Ancient Fauna of Nebraska," p. 55, Plate IV., Fig. 6. 



