vi LETTER OF TRANSMITTAL. 



The present volume includes Part I, and the first j)ortion of Part II as 

 far as the Ungulates; including, therefore, the Marsupials, Bats. Insectivores, 

 Rodents, and Garni vora of the Miocene. 



Part I includes the folh)winL'' ninst important contrihutions to paleon- 

 tology and evolution: 



1. The discovery of the fauna of the Puereo Gruu)), <>f thirty genera 

 and sixty-three species. This includes many important details, such as the 

 discovery and definition of three new families, with many species of a new 

 order, the Taxeopoda, as the PeripUfchidcE, Meniscotheriidce, and a new sub- 

 order, the Taliffrada, represented li\' tlie genus Pantolamhda ; also the dis- 

 covery of the Plagiaulax type (of the Jurassic) and other Marsupials, and 

 the Laramie Saurian genus Champsosaurus in the Puerco Group. 



2. The new classification of the Ungulata rendered possible by the dis- 

 covery of the complete remains of the Wasatch types of Pheuacodns and 

 Coryphodon, especially the former, from Wyoming Territory. The light 

 thrown on the phylogeny of the Ungulata by this discovery exceeds that 

 derived from all other sources together. 



3. The new classification of the lower clawed niaimnals, liased on the 

 analyses of fifteen new genera- and forty-seven new species of fiesh-eaters, 

 and six new genera and sixteen new species of allied forms, all discovered 

 since the publication of the author's volume in connection with the Wheeler 

 Survey. 



4. The restoration of Hyracotherium, the four-toed horse of the Wasatcli 

 Group. 



h. The restoration of the genera TripU)piis and llyracliyus of the 

 Bridger Fauna. 



6. The detenniiiatidii of tiu; systematic relation of the Dinocerata as 

 seen in the genera Loxolojihodon and Bathyopsis. 



The wiiole mnnber of genera described in this volume is 125, and 

 of species .■J4!i, of which 317 species were determined by Professor Cope. 



The explorations that furnished the materials for these volumes began 

 in 1872, and are still being continued. If will tlierefore be readily seen 

 that the amount of new matter towards tlie origin ami history of the Mam- 



