80 



THE MERYCOIDODONTID^ 



Eporeodon montanus (Douglass) 1907 

 Fig. 40 ; PL IX, figs. 1-3 



Original Reference: Some new merycoidodonts. Ann. Carnegie Mus., IV, pp. 100-101, pi. XXIII 

 (Eucrotafhus montanus). 



Type Locality: Near Stubb's old ferry on the Missouri River, about eleven miles northeast of Helena, 

 Montana. 



Geologic Horizon: Middle Oligocenc (top of lower Brule, in a soft, sandy deposit). 



Type: Holotype, Cat. No. 907 CM., skull and mandible, with pelvis, sacrum, and nearly all the presacral 

 vertebras. Collected by E. Douglass, 1903, and named after the state of Montana. 



Specific Characters: The skull is nearly the size of that of E. major but is closer to the 

 dolichocephalic type. The zygomata attain their maximum expansion at about the middle of the 

 zygomatic foramina. The malar is but moderately deep, and the squamosal process is lighter and 



Fig. 40. — Eporeodon montanus (Douglass). Skull and jaw. HT. 



(After Douglass, 1907.) 



Cat. No. 907 CM. 1/2 nat. size. 



rises sharply toward the posterior portion. The nasal bones are long and posteriorly truncated. 

 The -pars facialis of the lacrimal is large and the fossa small but very deep. The frontals are of 

 average width and moderately flat. They extend well in advance of the lacrimals, although this is 

 not shown in Douglass' figure of the type. The orbits are large. The temporal ridges unite over 

 the anterior part of the glenoid surface. The sagittal crest is high, thin, and approximately a trifle 

 less than one-third of the skull length. The supraoccipital crest is much produced, and the wings 

 are very slightly spread. The brain case is narrow, elongate, and low. The external auditory 

 meatus is large and somewhat posteriorly directed. The palate is narrow and moderately flat, with 

 the V-shaped palatonarial border behind the last molars. The basicranial axis is rather steep. The 

 glenoid articular surface is medium-sized. The postglenoid process is quadrilateral in basal outline 

 and terminates interiorly in a transverse ridge, a departure from the usual generic form. The 

 medium-sized bulla? are strongly compressed transversely to a narrow oval outline at the base. The 



