Peterson: The Osteology of Promerycochcerus. 215 



With the exception of the lighter build and shorter length of the 

 metatarsals these bones in P. vantassalensis do not greatly differ from 

 those of P. carrikeri. The phalanges are broad, depressed, and short. 



Measurements. 



No. 1230 

 (Type) 

 Mm. 

 Pelvis, diameter from point of ilium to ischial tuberosity 228 



Pelvis, diameter from point of ilium to middle of acetabulum 155 



Pelvis, greatest transverse diameter of both ilia when in position. . . . 285 



Pelvis, transverse diameter of pelvic cavity opposite the acetabula. . 100 



Pelvis, transverse diameter of pelvic cavity, posteriorly 95 



Tibia, greatest length 198 



Tibia, transverse diameter of the head 53 



Tibia, antero-posterior diameter of the head, approximately 50 



Tibia, antero-posterior diameter of distal end 24 



Tibia, transverse diameter of distal end 34 



Calcaneum, length, approximately 78 



Calcaneum, antero-posterior diameter at sustentacular facet 31 



Calcaneum, antero-posterior diameter at tuber calcis 24 



Calcaneum, transverse diameter of tuber calcis 12 



Tarsus, height 60 



Tarsus, breadth 43 



. Astragalus, height 42 



Astragalus, breadth 27 



Concluding Observations. 



The foregoing pages represent an effort to elucidate the osteology 

 of one genus of the Agriochoeridae, a family which comprised numerous 

 genera and species exclusively North American, which became extinct 

 in the latter part of the Tertiary. The family apparently was well 

 established in the late Eocene (Uinta), though at that early time show- 

 ing many affinities to the Tylopoda, as was true also of many other 

 artiodactyls at that period, as has been pointed out by Scott.-^ 



Before concluding it remains for the writer to present some views 

 which he holds as to the geology of the region where these specimens 

 were found, and to add a few remarks as to the evolution and phylo- 

 genetic relationships of the genus Promerycochcerus and its allies. 



The Upper and Lower Harrison beds in western Nebraska and eastern 

 Wyoming constitute two horizons, having together a thickness of less 

 than four hundred feet. They are superimposed upon one another 



22 "Uinta Selenodonts," Trans. Wagner Free Institute of Science, Vol. VI, 1899, 

 pp. 15-126. 



