334 Wortman — Studies of Eocene Mammalia in the 



succeeding mammalian development. This fact was fully 

 appreciated by Professor Marsh, and he spared neither pains nor 

 expense in making the collections as complete as possible. 



In 1871, he issued his first paper descriptive of these dis- 

 coveries, in this Journal (vol. ii, August, 1871) and in succeeding 

 years many publications in the same Journal were added. A 

 few groups, Dinocerata, Coryphodontia, and Tillodontia, were 

 described and illustrated in extenso, but by far the larger part of 

 the collection has either not been studied or only a few specimens 

 described in a brief preliminary way, mostly without illustration. 

 For many years prior to his death, he had fully recognized the 

 importance and desirability of having this subject, which the 

 press of many matters had prevented his undertaking, finally 

 and fully investigated for the sake of the advancement of the 

 science. The Trustees of the Museum have, therefore, gener- 

 ously placed at my disposal this entire collection for study and 

 publication, and it is to be earnestly hoped that the results 

 obtained will prove commensurate with the importance of the 

 undertaking. It is a source of the keenest regret to the author 

 that the investigation could not have been made under the 

 tutorship of the master whose ripe judgment and kindly 

 advice would have proved so helpful and such a tower of 

 strength in the preparation of the work. The subject will be 

 considered group by group, omitting those that have been 

 already fully published. The first of the series deals with 

 the Carnivora, after which the Primates and other orders will 

 follow. A consideration of the relationship of the horizons 

 in which these fossils occur will be reserved for the latter part 

 of the paper. 



Part I. Carnivora. 



In this group, I mean to include all those forms which are 

 usually classified as the modern Carnivora, together with their 

 extinct representatives commonly arranged under the ordinal 

 group Creodonta. That all the modern Carnivores have arisen 

 from and are directly traceable to what has been formerly 

 known as the Creodonta is now coming to be so well estab- 

 lished that from time to time it becomes necessary to modify 

 our ideas of their classification and arrangement. According to 

 the present state of evidence it seems probable that there were 

 at least three if not more points of contact where the two 

 groups actually unite. For this reason the distinction of one 

 from the other becomes a more and more difficult task. I 

 purpose, therefore, in the following treatise to consider the 

 entire series as constituting a single homogeneous order, the 

 origin of which dates back to Pretertiarv times, along with the 

 Edentates, Ungulates, and very probably, also, with the Insec- 



