Troxell — Hyrachyus and its Subgroups. 49 



References. 



Cope, E. D. 1873. On some Eocene mammals obtained by Hayden's Geo- 

 logical Survey of 1872. Pal. Bull. No. 12. 



— 1881. The Vertebrata of the Tertiary formations of the West. Eept. 

 U. S. Geol. Survey Terr., 3, 657-77. 



Leidy, Joseph. 1870. [Remarks on a collection of fossils from the western 

 territories.] Proc. Acad. Nat. Sei. Philadelphia, 22, 109. 



— 18 71 A. Eeport on the vertebrate fossils of the Tertiary formations of 

 the West. U. S. Geol. Survey Wyoming and portions of contiguous 

 Territories, 2d (4th) Ann. Eept. 



— 1871B. Remarks on fossil vertebrates from Wyoming. Proc. Acad. Nat. 

 Sci. Philadelphia, 23, 229. ' 



— 1873. Contributions to the extinct vertebrate fauna of the western terri- 

 tories. Rept. U. S. Geol. Survey Terr., 1. 



Marsh, 0. C, 1871. Notice of some new fossil mammals from the Tertiary 

 formation. This Journal (3), 2, 35-44. 



— 1872. Preliminary description of new Tertiary mammals. Ibid. (3), 4, 

 122-128. 



Osborn, H. F., Scott, W. B., and Speir, Francis, Jr. 1878. Palseontologieal 

 report of the Princeton scientific expedition of 1877. Contrib. Mus. 

 Geol. and Arch. Princeton Coll., 1. 



Am. Jour, Sci.— Fifth Series, Vol. IV, No. 19. — July. 1922. 

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