B. Uinta Selenodonts. 



Family I. CAMELID.E. 



Protylopus Wortman. 



Plate II., Figures 5-9. 



Bull. Am. Mus. Nat. Hist., vii., p. 104. (April 9, 1898.) 



Parameryx Scott {tion Marsh), Proc. Am. Phil. Soc, xxxvii., p. 74. (April 15, 1898.) 



IN my preliminary paper (loc. cit), which was printed but a few days after 

 that of Dr. Wortman, I referred this genus to Parameryx Marsh, with the 

 extremely vague and unsatisfactory descriptions of which it seemed to agree. 

 Dr. Wortman, who has seen the type specimens of the so-called Parameryx, 

 is satisfied that the present genus is distinct from it. He has given ('98, pp. 

 104-1 10) an excellent outline description of this animal, the phylogenetic im- 

 portance of which it is difficult to exaggerate, but a somewhat more detailed 

 account is necessary for the purposes of this paper. As this genus almost 

 certainly represents the main line of tylopodan descent in Uinta times, the line 

 which has led to the modern camels and llamas, it will serve as an admirable 

 standard of comparison by which to test the divergences of its contempora- 

 ries. Protylopus is of very great interest as being the most ancient undoubted 

 member of the tylopodan line, though it sheds less light than could be 

 desired upon the relations of that line to the other artiodactyl series, for 

 the peculiar differentiation which is so strongly marked in the White River 

 genus, Poebrotherium, is already distinct in the Uinta form. 



I. The Dentition. The dental formula is unreduced, If, Cy, Pf, Mf , and 

 in both jaws the teeth form straight and almost continuous series, slightly 

 spaced apart, it is true, in the anterior region, but without anything that can 

 be fairly called a diastema. 



A. Upper Jaw. (Plate II., figs. 5, 6.) The incisors are small and are 

 arranged in a nearly straight fore-and-aft line, curving inward but very slightly 

 at the anterior end ; they increase somewhat in size from the first to the third, 

 and are separated by moderate interspaces, with a rather longer space between 



