286 Thorpe — New Germs of Oligocene HycBnodontidce. 



Hyamodon. 



Glenoid articular surface on level with basicranial plane. No 

 external buttress on M 3 . 



A. Superior premolars three. Face short. 



1. Length of superior molar-premolar series 62 mm. 



H. paucidens 



B. Superior premolars four. Dolichocephalic. 



1. Palatines in contact throughout ; pterygoid pro- 



cesses suturally joined. Length of superior 

 molar-premolar series 74 mm. . H. leptocephalus 



2. Posterior nares opening between palatines. 



a. Postorbital constriction in advance of coro- 



nal suture. 



(1) Length of superior molar-premolar 

 series 72 mm H. crucians 



b. Postorbital constriction at or behind coronal 



suture. 



(1) Size large. Length of superior 



molar-premolar series 106 mm. 



H. cruentus 



(2) Size moderate. Complete skull un- 



known. Length of superior 

 molar-premolar series 83 mm. 



H. montanus 



(3) Size small. Length of superior 



molar-premolar series 58 mm. 



H. mustelinus 



Eeferences. 



Andrews, C. W. 1906. A descriptive catalogue of the Tertiary Vertebrata 

 of the Fayum, Egypt. London. 



— 1907. The recently discovered Tertiary Vertebrata of Egypt. Ann. 



Eept. Smithsonian Inst., for 1906, 295-307. 



Douglass, E. 1901. Fossil Mammalia of the White Eiver beds of Mon- 

 tana. Trans. Amer. Philos. Soc, n. s., 20, 237-279. 



Filhol, H. 1876. Eecherches sur les phosphorites du Quercy. Etude des 

 fossiles qu'on y rencontre et specialement des mammiferes. Ann. Sei. 

 Geol., ser. 4, 7. Art. 7. 



Laizer and Parieu. 1839. Note sur la machoire d'un carnassier fossile, 

 nomme Hyenodon leptorliynchus. Ann. Sci. Nat., (2), 11, 27-31, pi. 2. 



Leidy, J. 1853. [Eemarks on a collection of fossil Mammalia from 

 Nebraska.] Proc. Acad. Nat. Sci., Philadelphia, 6, 392-394. 



— 1869. The extinct mammalian fauna of Dakota and Nebraska. Jour. 



Acad. Nat. Sci., Philadelphia, (2), 7. 

 Lydekker, E. 1885. Catalogue of the fossil Mammalia in the British 



Museum (Natural History), pt. I. London. 

 Marsh, O. C. 1884. Dinocerata. U. S. Geol. Survey, Mon. 10. 

 Matthew, W. D. 1901. Additional observations on the Creodonta. Bull. 



Amer. Mus. Nat. Hist., vol. 14, 1-38. 



