THE OSTEOLOGY AND RELATIONS OF 

 PROTOCERAS. 



W. B. SCOTT. 



{^Investigation aided by a grant frovi the Elizabeth Thompson Fund of the A.A.A.S.) 



No group of mammals offers greater difficulties in the way 

 of arranging all its members in their order of relationship to 

 one another than the Artiodactyla. These difficulties arise 

 largely from the great number of extinct genera which are 

 very imperfectly known from fragmentary remains, and as a 

 consequence of this it is frequently impossible to determine the 

 taxonomic values of resemblances and differences. The first 

 step toward bringing order out of this chaos must consist in 

 completing our knowledge of the structure of the many imper- 

 fectly known genera, and wherever it is possible, in carefully 

 tracing out all the cases of parallel or converging development 

 in one or other organ, where it can be shown to have taken 

 place. In this way we may hope eventually to bring together 

 such a body of facts as will clear up these complicated relation- 

 ships. The Princeton Museum has recently obtained, thanks 

 to the energy and skill of Mr. Hatcher, very extensive and 

 wonderfully preserved collections of Tertiary mammals from 

 the Western States, comprising many nearly complete skele- 

 tons of artiodactyls hitherto known only from scattered frag- 

 ments. As soon as this material can be prepared, it is my 

 purpose to render it available for comparison by careful descrip- 

 tion and full illustration. The perhaps tedious minuteness of 

 such descriptions cannot well be avoided, if the object in view 

 is to be effectively served. 



The extraordinary genus Protoceras (Marsh) is one of those 

 which will best repay exact and minute study, for, although its 

 systematic position is far from clear, for reasons which will 

 appear later, yet it throws much welcome light upon the mode 

 of development among the artiodactyls, and shows how it has 



