1903.] Matthew, Faima of Titanotherium Beds of Montana. 207 



much narrower, especially the talonid, in which the hypoconulid is 

 situated more behind the hypo- and entoconid instead of nearly be- 

 tween them. 



The skull is wider between the eyes than those from the 

 Oreodon Beds, the postorbital constriction less pronounced. 

 The temporal crests begin on the posterior third of the frontal 

 bones, eleven millimeters apart, and converge rapidly on the 

 posterior half of the parietals. 



The humerus is disproportionately smaller and more curved 

 than in 7. dakotensis, the deltoid crest is not so wide nor does 

 it extend so far down. The radius is likewise strongly curved, 

 its distal end bearing two ill-separated subquadrate facets for 

 scaphoid and lunar, the scaphoid facet the wider of the two. 

 Two rather long and slender phalanges are preserved, one 

 somewhat compressed laterally. The caudal vertebra asso- 

 ciated is from the middle part of the series and indicates a 

 large, long tail. 



This species is in some, but not in all respects intermediate 

 between Palmctops and the Leptictidae of the Oreodon Beds. 

 The last molar is more reduced than in P. hicnspis, less than 

 in any later Leptictid. The first premolar is one-rooted, as 

 in P. bicuspis, while in the later species it is two-rooted. On 

 the other hand, the molars are more compressed and more 

 constricted medially, and the size is smaller than in either the 

 Wind River species or those from the Oreodon Beds; and the 

 temporal crests are further apart than in the later species, 

 while in the earlier one they are united into a sagittal crest. 



Ictops thomsoni, spec, no v. 



Two upper jaws, Type, No. 9606, Cotype, 

 No. 9606a, indicate a species closely allied 

 to Ictops aciitidens, but distinguished by 

 smaller size, more compressed teeth, and 

 other characters of less importance. The 

 metacone on all the molars is decidedly son)^' CroJn'''*view'"of 

 smaller than the paracone ; in I. aciitidens specimen.*"' ^ ^' ^^^ 

 they are nearly, and in other Leptictidas 

 quite, equal in size on m^" 2. The protocone on p4-m3 is more 



