18 Wortman — Studies of Eocene Mammalia in the 



There are three or four individuals that agree perfectly with 

 the type and cotvpe, but there are others that have a heavier 

 build aud are j^erceptibly larger. I cannot detect any further 

 differences in the materials at hand, however, which would 

 warrant referring the latter to another species. It may be 

 that more complete specimens will necessitate their separation. 

 Additional characters derived from these specimens are : 

 Second lower molar equal to, or slightly larger than, third ; 

 last superior molar without postero-external cusp, and second 

 superior molar, as well as first, with distinct internal cingula. 



The measurements of the type are as follows : 



Length of inferior dental series from base of canine, 



exclusive of last molar „._. 42" °^™ 



Length of premolars 30' 



Length of tirst and second molars ...'.' 12' 



Length of entire inferior dental series (estimated) .__. 48*5 



Antero-posterior diameter of first molar „. 6* 



Antero-posterior diameter of second molar 7* 



Antero-posterior diameter of third molar (not type) 6*4 



Measurements of Cotype. 



Length of fourth premolar and first molar . _ 13- 



Antero-posterior diameter of fourth premolar _ 6* 



Antero-posterior diameter of first molar _ 7* 



Transverse diameter of fourth premolar 5- 



Transverse diameter of first molar 4*6 



* 



The type specimen was found by Professor Marsh, at Griz- 

 zly Buttes, and the cotype, by Mr. Kinney, at the same locality. 

 Other specimens are from Church Buttes, and one is doubtfully 

 from Henry's Fork. 



Smopa major sp. no v. 



The last species of this group to be considered is the largest 

 yet found in the Bridger horizon. It is apparently unde- 

 scribed, and the above name is proposed for it. Two reason- 

 ably complete mandibular rami, figures 98, 99, one of which 

 contains nearly all the teeth in place, together with three or 

 four other fragmentary pieces carrying various teeth, repre- 

 sent it in the collection. The type specimen has the three 

 molars and the third and fourth premolars in place in the jaw, 

 together with the roots and alveoli of the remaining premolars. 

 The chief characters of the species, as exhibited by this speci- 

 men, may be stated as follows : It is much larger than S. edax^ 

 S. gracilis^ or S. minor ; the second premolar is separated but 

 very slightly, if at all, from the third ; the first is small, single- 

 rooted, and placed about equidistant from the canine and 

 second premolar ; the second molar is slightly larger than the 



