432 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



Type-locality. — Bad Lands, about 3 miles nortlieast of Buford 

 (Fort Union of early days), North Dakota. 



Horizon. — Paleocene, Fort Union formation (type section). 



Diagnosis. — Teeth indicate an animal about the size of the smaller 

 Paleosijops of the Bridger or of one of the smaller species of Caenopus 

 of the Oligocene; talonid of last molar relatively elongated with large 

 hypoconuhd which shows distinct evidence of buddmg off to form a 

 third lobe; talonid of molars relatively low and narrower than the 

 trigonid; basal cingulum continuous except on lingual border of 

 crowns, talonid of pO)^ rudimentary being little more than a cingu- 

 lum cusp situated almost in hue with the inner cusps row at the base 

 of the metaconid ; cusps of the trigonid, both in the molars and in jh) 

 relatively high and pointed. 



Measurements. 



Anteroposterior. Transverse. 



ifi 22. 5+ 15. 5 



M^ 27 19 



Ms 32. 8 19. 4 



P4(?) 5 14.5 



Discussion of cliaracters and possiUe relationships. — The specimen 

 constitutmg the type above described wliile very fragmentary for- 

 tunately is of a young adult in which only mj of the tooth series shows 

 any degree of wear and all the teeth are well preserved, hence what 

 characters they possess are not confused. 



This species represents by far the largest mammal yet known from 

 the Paleocene. The teeth are about one-third larger than those of 

 the largest species of Pantolamhda of this horizon, and about equal 

 those of CorypTiodon simus of the Wasatch or one of the smaller species 

 of Caenopus of the Oligocene. 



In the absence of other parts of the skeleton to substantiate the 

 evidence of tooth characters, the ordinal position of this animal ad- 

 mittedly does not stand on unassailable grounds. However these 

 teeth from the Fort Union seem certainly to be those of an ungulates 

 and their general characteristics suggest Titanothere affinities. 



Compared in detail with the Titanotheres they present similaritie, 

 which, when the much older horizon and consequently more primitive 

 stage of development is considered, are rather striking. These sim- 

 ilarities consist in (1) the like relative proportions of the molars to 

 each other in the series; (2) the correspondence in form and general 

 contour of the triconid and talonid, both of which are V shaped and 

 imiting form the W pattern characteristic of the Titanothere lower 

 molars; (3) the cingulam development is hke that observed in those 

 Titanotheres in which this element is present; and (4) the bone frag- 

 ments show the lower jaw to be of heavy massive type, with broad, 

 shallow and unsutured symphasis, while the canine and submental 



