100 Annals of the Carnegie Museum. 



rounded, and the sagittal crest low. The posterior portions of the 

 nasals are attenuated and the lachrymal pits shallow. The face is 

 concave above the premolars, especially anterior to the infraorbital 

 foramen, which is over P^. The tympanic bullae are very large and 

 high and are elliptical in horizontal section. The pit for the tym- 

 panohyal and the stylomastoid foramen are nearly equal in size. 

 The mastoid process is fairly heavy, but does not extend far downward 

 between the exoccipital and the external auditory meatus. The paroc- 

 cipital processes are five-sided at the base, four-sided lower down, and 

 three-sided near the tips. There is a postero-external ridge and the 

 antero-internal side, which is closely pressed against the postero-exter- 

 nal side of the bulla, is concave. There is no foramen rotundum. 



The crowns of the upper premolars incline backward or the outer 

 crescents have a long convex cutting border and a shorter concave 

 posterior border. The fourth upper premolar is different from that of 

 Merycoidodonts in general, in having two anterior fossettes as in P^, 

 P-2, and P^. 



The chin is slightly concave. The anterior border of the ascending 

 ramus of the mandible is nearly perpendicular and the coronoid 

 process is not deflected backward. There is a small sharp cusp on M^ 

 between the posterior external crescent and the heel, which I have not 

 observed in any other Merycoidodonts. 



The specific name refers to the prosperous town of Dickinson, 

 which is not far from the locality where the specimen was found. 



Measurements. 



mm. 



Length of skull, basal measurement 184 



Width of skull at posterior orbits 105 



Length of molar-premolar series 85 



Length of premolar series 40 



Length of molar series 45 



Eucrotaphus montanus sp. nov. 



(Plate XXIII.) 



(Type No. 907, Carnegie Museum Catalogue Vertebrate Fossils.) 

 The type, which was collected by Earl Douglass, 1903, consists 

 of nearly an entire skull with the mandible, a pelvis, a sacrum, and 

 nearly all the presacral vertebrae. It was found near Stubb's old 

 ferry on the Missouri River about eleven miles northeast of Helena, 

 Montana, in a soft, sandy deposit. This was the only good speci- 



