New Equine Mammals from the Tertiary Formation. 157 



and such information as he hopes may be of use to those who wish to 

 engage, practically, in the study of this most interesting and useful 

 branch of natural history. It is a great pleasure to have fine, perfect 

 specimens of any species for such study ; but the pleasure is much 

 greater when the student can say to his friend, that he has reared his 

 specimen from the egg, observed its entire habits of life, and secured 

 and preserved it himself, to be 



" A thing of bcaiily, and a joy forever." 



--ind this any earnest person can do, with a little careful observation 

 and pleasurable labor, and with great mental profit. To stimulate a 

 taste for such recreations, that give pure enjoyment without the possi- 

 bility of evil consequences, is the chief object of this article. 



Neiv Equine 3fammals, from the Tertiarxj Formation. By O. C. Marsh. 

 From The Kn\. Jour, of Sci. and Arts, for March, 1874. 



Prof. Marsh has described some new equine mammals from the Ter- 

 tiary formation of the western territories, in the March number of the 

 American Journal of Science and Arts, and thrown a great deal of 

 light on the origin of the horse. He has described a genus under the 

 name of Oruhippus, from the Eocene of Wyoming and Utah, the skel- 

 eton of Avhich, in its general features, is decidedly equine, but the ani- 

 mal was only about the size of a fox. Another, under the na&e of 

 Miohipims, from the Miocene of Oregon, somewhat exceeding a sheep 

 in size, and with longer limbs. And another, under the name of 

 Pliohippus, from the Pliocene of the Niobrara River, about the size of 

 the ass. He says in conclusion : 



"The large number of equine mammals now known, from the Ter- 

 tiary deposits of this country, and their regular distribution through 

 the sub-divisions of this formation, afford a good opportunity to ascer- 

 tain the probable lineal descent of the modern horse. The American 

 representative of the latter is the extinct Eqims fraternis (Leidy), a 

 species almost, if not entire!}', identical with the old world Equus cahal- 

 lits (Linn), to which our recent horse belongs. Huxley has traced 

 successfully the latter genealogy of the horse through European ex- 

 tinct forms, but the line in America was probably a more direct one, 

 and the record is more complete. Taking them as the extreme of a 

 series Orohippxis agilis (Marsh), from the Eocene, and Equm fraternis 

 (Leidy), from the Quaternary, intermediate forms may be intercalated 



