320 A NEW MYLODON. 



nebrascensis. Of the first, Owen's classic memoir (1842) treats in detail, and the 

 Museum possesses a mounted skeleton from the Pampas formation of Argentina. 

 No complete account of the North American M . harlani has been published, and 

 since the type consisted of but a portion of the lower jaw with the teeth, some 

 doubt attaches to the identification of other fragments of the skeleton later 

 referred to the same species. Cope (1895) first described and figured what 

 are doubtless the upper teeth of this animal, and Loidy and others have described 

 and figured bones which are believed likewise to represent it. No complete 

 skull seems to have been found, but Cockerell in 1909 published an account of 

 a cranium without teeth from Colorado which, after careful comparison of photo- 

 graphs, I believe is identical with M. harlani. To the same species are probably 

 referable the teeth on which Cope founded Mylodon renidens and M. sulcidens, 

 names currently included in the synonymy of M. harlani. Cope's Mylodon 

 sodalis, based on an ungual phalanx, remains unknown. The description of 

 M. garmani follows. 



The skull (Plates 1, 2) except for the loss of a few chips here and there, is 

 practically perfect and is clearly that of an adult animal. In general outline it 

 resembles that of other species of Mylodon, but is extremely narrow. The dorsal 

 profile is a nearly straight line with a slight depression above the orbit (in tlie 

 specimen the actual depression is accentuated through a slight crushing in of the 

 skull). The palatal profile is nearly parallel with the general dorsal outline but 

 its plane if produced backward, would pass nearly through the center of the 

 occipital condyles, as in Paramylodon. The pterygoids extend downward 

 from the palatal plane to a distance about equal to one half the height of the 

 braincase. The rostrum in side view is abruptly truncate, its general outline 

 nearly at right angles to the dorsal profile. The upper half is convex, the lower 

 half nearly vertical, or slightly concave, thus resembling Cockerell's specimen 

 from Colorado, here considered M. harlani, but differing from Paramylodon, in 

 which the lower half extends gently forward and downward. The maxillae 

 and premaxillae extend some 80 mm. in advance of this boundary. The pos- 

 terior profile of the skull is gently and evenly convex, beginning at a point on the 

 dorsal margin directly above the posterior base of the squamosal process. Its 

 curve if continued passes through the posterior third of the occipital condyle, 

 thus more as in Paramylodon than in the Colorado skull whose condyles lie 

 mostly outside the posterior outline of the cranium. 



In dorsal view, the most striking character is the extreme narrowness of 

 the braincase, whose greatest breadth, measured at the junction with the 



