2 



osborn: OLIGOCENE, MIOCENE, PLIOCENE EQUINE. 



PREFACE AND ACKNOWLEDGMENTS. 



The systematic revision of the fossil horses of North and Central America has been in progress under the direction 

 of the author since the year 1900 in preparation for his " Monograph of the Equidse." The work in the American Museum 

 of Natural History has been carried on with the cooperation of James Williams Gidley, Walter Granger, and William Diller 

 Matthew. Recently Oliver Perry Hay of the Carnegie Institution, Washington, has continued the revision of the Pleisto- 

 cene species of Equus which was begun by Gidley. John Campbell Merriam of the University of California through his 

 explorations has added an important series of Miocene and Pliocene species from the central desert and Pacific coast 

 regions. The author's acknowledgments are due also to the writings of Earl Douglass, 0. A. Peterson, Erwin H. 

 Barbour, Richard Swann Lull, Edward L. Troxell, and E. H. Sellards. 



Systematic Revisions. — The published and manuscript revisions by the American Museum as completed or in progress 

 are chiefly as follows: 



Titles Reference in Text 



Gidley, J. W. 



"Tooth Characters and Revision of the North American Species of the Genus Equus," Bull. Amer. Mus. Nat. 



Hist., Vol. XIV, Art. IX, May 31, 1901, pp. 91-142, plls. XVIII-XXI, 27 text figs. . . . (Gidley, 1901) 



"Proper Generic Names of Miocene Horses," Bull. Amer. Mus. Nat. Hist., Vol. XX, Art. XV, May 28, 190-4, 



pp. 191-194 (Gidley, 1904) 



"Revision of the Miocene and Pliocene Equidre of North America," Bull. Amer. Mus. Nat. Hist., Vol. XXIII, 



Art. XXXV, Nov. 26, 1907, pp. 865-934 (Gidley, 1907) 



Matthew, W. D., and 

 Gidley, J. W. 



" New or Little Known Mammals from the Miocene of South Dakota, Part IV, Equidse," J. W. G. Bull. Amer. 



Mus. Nat. Hist., Vol. XXII, Art. VIII, May 26, 1906, pp. 135-154, 20 text figures (Gidley, 1906) 



Osborn, Henry Fairfield. 



"New Oligocene Horses," Bull. Amer. Mus. Nat. Hist., Vol. XX, Art. XIII, May 28, 1904, pp. 167-179, pis. 



IV, V, 8 text figs (Osborn, 1904) 



Granger, Walter. 



"A Revision of the American Eocene Horses, "Bull. Amer. Mus. Nat. Hist., Vol. XXIV, Art. XV, Mar. 25, 



190S, pp. 221-264, pis. XV-XVHI, 5 text figs (Granger, 1908) 



Matthew, W. D. 



(MS.) During the year 1912-13 Dr. W. D. Matthew undertook the study of the Upper Oligocene, Miocene, and 

 Pliocene Equidse in the collections of the American Museum of Natural History, compiling also notes on 

 the systematic revision of the types of new genera and species and on the phylogenetic or evolutionary 

 relationships of the Miocene and Pliocene equines ........... (Matthew, 1913) 



The author is chiefly indebted to the original researches by Matthew mentioned above (Matthew, 1913) on the 

 Miocene and Pliocene species of Equidae in the collections of the American Museum of Natural History. At first a 

 joint report was contemplated; but for certain reasons it has appeared wiser that the present revision should appear under 

 a single name. The author issues it, therefore, with the fullest acknowledgment of his indebtedness to his colleague, 

 from whose descriptions, observations, and definitions many quotations are taken entire without amendment. On 

 certain points of difference of interpretation and opinion which have arisen the author holds himself solely responsible. 



In this revision the author has been aided constantly also by Professor J. C. Merriam, who has furnished a complete 

 series of type illustrations, and in addition to his published works has contributed invaluable notes. 



Professor R. S. Lull has contributed all the records which have been preserved regarding the type materials in the 

 Marsh collection of the Peabody Museum, Yale University. 



The manuscript has been prepared and the proofs corrected chiefly by Miss H. Ernestine Ripley. 



Illustrations. — The present revision is iconographic in the sense that all the original type figures of authors are re- 

 produced in facsimile, and all unfigured types, especially those of Marsh, are now figured for the first time, chiefly from 

 the remarkable pencil drawings of the two Japanese artists Mr. S. Oka, who worked at the American Museum from 

 Nov. 1, 1901, until April 30, 1903, and Mr. Binya Yoshihara, who worked from Feb. 1, 1904, until Jan. 31, 1907. It is 

 a pleasure to acknowledge the skill and fidelity of these accomplished artists, whose drawings will be reproduced by 

 lithography in the author's " Monograph of the Equidte." The present memoir is illustrated also by fifty-four com- 

 parative plates executed in 1912, 1913, 1915, 1916, by Mrs. Lindsey Morris Sterling under the direction of the author 

 and Dr. W. D. Matthew. 



