266 THE WASATCH xVND r.lMDGKi; FAUN^. 



IcTOPS Bicuspis Cope. 



Bulletin U. S. Geol. Snrr. Terrs., vi, 1881, p. 192. Stypolophug bicuspis Cope, American Naturalist, 1880, 



p. 746, October. 



Plate xxix a, figs^ 2-3. 



This species is represented by a skull with mandible, from which the 

 occiput is broken away. From it I have developed the entire dentition of 

 one side, and nearly all of that of the other. The skull is about the size 

 of that of a mink, and has the form of that of a civet. 



The premaxillary bone is remarkably extended anteroposteriorly, 

 opposite the nares. The muzzle is moderately elongate, and is contracted 

 laterally. The orbits are not defined posteriorly. The anterior temporal 

 ridges are very obscure, and early unite into a low sagittal crest. The 

 zygoma is proportionately very slender. The glenoid cavity is quite wide, 

 and the postglenoid process is well extended transversely. The infraor- 

 bital foramen issues above the anterior border of the first true molar. 

 There are short diastemata behind the posterior incisor, and behind the first 

 and second premolars. The first premolar is situated close to the canine. 



The crowns of the canines are compressed and rather short, with the 

 anterior edge subvertical, and the posterior oblique. The latter is also 

 acute. Crowns of second and third superior premolars compressed, with a 

 prominent cusp behind the principal one. First and second true molars 

 with two distinct external cusps and a strong external basal cingulum. 

 The posterior basal cingulum is strong, almost developing a posterior inter- 

 nal cusp in the first and second. There are no external cingula on the 

 third and fourth premolars, excepting a short one opposite the posterior 

 cusp of the fourth Inferior first premolar one-rooted, third with a posterior 

 heel, and fourth with strong anterior and especially posterior heels. Heels 

 of true molars well developed, cuspidate, the external lobe having a cres- 

 centic section, and separated from the internal by a small median tubercle. 

 The latter is strongest on the last molar, giving the heel greater length. 

 The anterior internal cusp of the crown is much larger on the fourth 

 inferior premolar than on the true molars, where it is absolutely median in 

 position. 



The mandibular ramus is slender, and the inferior border is gently 



