Preface. VU 



mens to the collections, including- some thirty more or 

 less complete skeletons, eight of which have already 

 been mounted and placed on exhibition, as follows : 



Eqinis scotti. JMcrycodus osborni. 



Ornitholcstes hernianni. GlyptotJicriiim texmiiim. 



Hypohippiis eqidims. Dinictis squalidens. 



Neohippardou ivhitneyi. Cynodictis gregariiis. 



RECENT EXPLORATIONS. 



Exploration for Dinosaurs. — A large part of 

 the field work of the Department since 1897 has 

 been directed to securincr the remains of Dinosaurs, 

 especially from the Upper Jurassic (Como Beds) of 

 Wyoming and Colorado, and from the Cretaceous. 

 A rich and extensive deposit, the " Bone Cabin 

 Quarry," was opened up in Wyoming in 1898, and 

 has been worked with good results for six years. 



Evolution of the Horse. — The generosity of 

 one of the Trustees of the Museum, Mr. William C. 

 Whitney, enabled the Curator to send out in 1899 

 and subsequent years a series of expeditions into 

 various Tertiary formations of which the chief object 

 was to obtain materials to illustrate the evolution of 

 the horse. 



GEOLOGICAL RESULTS. 



The field parties beginning in 1900 have with one 

 or two exceptions made very exact stratigraphical 

 field records. The result is the accumulation of im- 

 portant data concerning the distribution of faunas and 

 especially concerning the subdivision of horizons which 

 were formerly considered single or incorrectly identi- 

 fied. We may summarize these results since 1900 as 

 follows : 



