1 898. J IVortinan, Extinct Camclidcc of N^orth America. I 19 



Fig. iS. Ulna and 

 radius of Goinflio- 

 theriiiin cameloides. 



The exact stratigraphical position of this species is several hun- 

 dred feet above that of G. sternbergi, and there can be no doubt 

 whatever that G. cameloides is not only the direct lineal descend- 

 ant of the older species, but is, at the same time, the progeni- 

 tor of the succeeding Loup Fork species. This conclusion is 

 somewhat at variance with the view expressed by Scott,' in 

 which he says : " The Camels of the John Day formation do not 

 present any imjjortant modifi- 

 cations of the dentition ; in 

 some of them the first upj^er 

 premolar has but a single fang, 

 and others are decidedly re- 

 duced in size ; the former Cope 

 has erected into a separate 

 genus, Gomphotherium. It seems 

 probable that these forms are 

 not in the direct line of the 

 cameline descent." A careful 

 examination of Cope's type of 

 Gomphotherium sternbergi, the 

 only species, by the way, with 

 the exception of the one above 

 named, Avhich has so far been 

 described from these beds, re- 

 veals the fact that the first 

 superior premolar, instead of 

 being a single-rooted tooth, is 

 strongly two- rooted ; and that 

 the succeeding premolars ex- 

 hibit a most interesting and in- 

 structive transitional stage be- 

 tween Poebrolhcrium and Pro- 

 tolabis, not only as regards their 

 form but their degree of re- 

 duction as well. I have been unable, after the most exhaus- 

 tive study, to find any evidence wliatever tending to show that 



Fig. I ). Fore foot 

 >f Goiiiphotlierium 

 aiiieloidfs. 



1 ' The Osteology of Poebrotherium," i8qi, p. 41.3. 



