974 THE JOHN DAY FAUNA. 



but the skull and dentition are those of a true saber-tooth, and there seems, 

 to be no ground for believing the Musteline affinities suggested by Leidy.^ 

 It occupies the lowest position on the line of the saber-tooths, on account 

 of its numerous and simply constructed molar teeth, and stands in immedi- 

 ate connection with the false saber-tooth group, having exactly the dental 

 formula of ^lurogale Filh. On this account I formerly united the two 

 genera, but now believe that the absence of the inferior flange of the man- 

 dible in ^lurogale is sufficient ground for maintaining them as distinct. The 

 latter genus, in this respect, exactly resembles Archcelurus and Nimravus. 



Remains of this genus are quite abundant in the White River forma- 

 tion in Nebraska and Colorado. They principally belong to the longest 

 known and typical species, D. felina Leidy. Specimens are much less 

 numerous in the John Day beds of Oregon. Two species have been 

 obtained from the former horizon, the D. felina and D. squalidens, and one 

 from the latter, the D. cyclops. The characters are as follows: 



3 1 3 ] 



Dental formula: I. -; C. -; Pm. -; M. -. The superior canine is long 



and compressed, and reposes against an inferior marginal flange of the 

 mandible, whose surface is separated from that of the symphysis by a 

 strong angle. Unworn incisors with wedge-shaped crowns. Superior sec- 

 torial without anterior basal lobe. Inferior sectorial with posterior cutting 

 heel, and an inner tubercle of small size. Postglenoid and postparietal 

 foramina present. No intermediate posterior lobes of the premolars. 



The three species may be distinguished by the following characters: 



First inferior molar two-rooted; first superior very small; cranium shorter behind. 



D. cyclops. 

 First inferior and superior molars two-rooted, the latter larger; cranium longer 



behind D. felina. 



First inferior molar one-rooted; mandibular flange short, rounded D. squalidens. 



DiNicTis CYCLOPS Cope. 



Proceedings Academy Philadelphia, lt-79, 176 (read July 8). American Naturalist, 1880, p. 846, fig. 8. 



Plate LXXV ; fig. 1. 



The profile of the skull is very convex, the planes of the nasal bones 

 and sagittal crest meeting at an angle of 135°. The place of the angle is 



'Extinct Mammalia, Dak., Nebr., p. 64. 



