Douglass: Vertebrates ikom Montana 'l"i;RriAkv. 103 



"White Ri\or selcnoilonts. It looks as though it might l)e a descend- 

 ant of Lcptoreodon. 



The dental formula is Ci, PA, M^. All are large and strong, except 

 P', which is small, but two-rooted. It is separated from the canine 

 and P^ by diastemata. It is a little nearer to P^ than to the canine. 

 The canine is, so far as preserved, of the usual Oreodont pattern, but 

 is more compressed laterally. P' is a laterally compressed subconical 

 cusp. The crown from the outside has a slight hint of the trifid ap- 

 pearance of the same view of P- and P- — that is, there are rudiments 

 of anterior and posterior cusps or lobes. P^ is large and has three 

 outer lobes. It is widest back of the middle. P is a little longer 

 and more triangular on account of the larger posterior inner lobe, 

 pi is of the usual pattern in ruminants. Premolars 2 and 4 are nearly 

 equal in length. Only portions of the molars are preserved, but the 

 teeth are large. The teeth back of Pl show much wear. 



The infraorbital foramen opens above the anterior portion of P"; 

 and the front margin of the orbit is above the anterior half of M^. 

 So far as I can ascertain from the crushed condition in this region 

 there w'-ere neither prelachrymal pits or vacuities. 



Measurements. 



Mm. 



From front of canine to front of orbit 5° 



Length of canine 4.3 



Width of canine 2,.'^ 



Length of diastema between C and r*'- 6 



Length of Pi 3.5 



Width of Pi 2 



Length of diastema between P' and P'.." 4 



Length of P- 7 



Width " " 4 



Length of P^ 9 



Width " " 5 



Length of Pi 7 



Width " " 7 



Length of M' 7-5 



I-ength of M- 9 



OrEODON MACRORHINUS Sp. nOV. 



No. 767. Fig. 8. 

 In my paper " Fossil Mammalia of the White River Beds of Mon- 

 tana " ' I described a species of Oreodo 1 under the name of " Oreodon 

 J Trans. Am. Phil. Soc, Vol. XX., p. 264. 



