Douglass: Vertebrate Fossils from Fort Union Beds. 15 



length of P-, with four external and six internal tubercles ; anterior 

 portioti of tooth narrower than posterior portion. 



The last premolar is larger than that of Ptilodus trouessartianus 

 Cope, but not so large as that of P. mediavus Cope. The longitudinal 

 valley on the first molar is broadly V-shaped. There are two perpen- 

 dicular ridges, separated by a median groove, on the inner surfaces of 

 each of the outer tubercles. From Silberling quarry, east of Bear 

 Butte. 



mm. 



Length of P^ 7.5 



LengthofMj- 3.7 



There are several fourth premolars in the Carnegie Museum collec- 

 tion (1682, 1683, etc.), and in the small collection loaned by Mr. Sil- 

 berling, which evidently belong to this species, also a first molar (No. 

 1684). There are other smaller teeth which probably belong to a 

 smaller species. 



No. 1933 is an upper molar tooth. It is rectangular in shape, 

 nearly square. Instead of having three rows of tubercles it has two 

 rows and a continuous ridge on which is one rudimentary tubercle. 

 There are four tubercles on the median and three on the outer row. 

 The tubercles are neither quite conical nor crescent-shaped, but are 

 intermediate between the two and are quadrangular at the bases. 



Order MARSUPIAL/A ? Marsh. 

 Family CIMOLESTID^? Marsh. 



Batodon? Marsh. 

 (Am. Jour. Sc. (3), XLIII, 1892, p. 258.) 

 A lower molar (Carn. Mus. Cat, Vert. Foss., No. 1693) somewhat 

 resembles the teeth figured by Marsh as Batodon tenuis, though there 

 is much doubt that it belongs to that species. The specimen is some- 

 what larger than the figure and the trigonid is higher. The heel is 

 low and has three low cusps, two lateral and one median, which bound 

 the basin of the heel posteriorly. 



mm 



Length of molar 3. 



Height of trigonid 2.9 



Another tooth (No. 1692, Plate I, Figs. 7-8) is of approximately 

 the same size, but is shorter antero-posteriorly. The anterior portion 

 is high and the two principal cusps equal in height. The posterior 



