A NEW MYLODON. 341 



he published a figure of the type phalanx, and in 1893, writes that he had since 

 received from George Duncan, of Paisley, Oregon, an imperfect symphysis 

 mandibuh from near the original locality. He doubtfully refers to M. sodalis 

 "the distal part of a femur, lacking part of the internal condyle and adjacent 

 epicondyle" from the Llano Estacado of Texas. It was found associated with 

 species of the Equus fauna similar to those of the Oregon beds at Silver Lake. 

 Matthew (1902) in his list of the Pleistocene fauna from Hay Springs, Nebraska, 

 gives a revision of Cope's list of species from Silver Lake, and includes Mylodon 

 sodalis as possibly synonymous with M. harlani. He also lists astragali and foot 

 bones of "Mylodon sp." from Washtuckna Lake, Washington, a new locality 

 for the genus. With regard to the ungual phalanx on which Cope founded M. 

 sodalis, Osborn (1910, p. 459) suggests that it may prove to be that of a Mega- 

 lonyx, but Cope's figure published in 1889, seems more nearly to resemble the 

 claw of Mylodon, and is less curved than the large claw of Megalonyx. The 

 original description states that the ungual phalanx "has its basal sheath devel- 

 oped on one side only; its place is taken on the opposite side by a prominent 

 rim, which is tuberculate and notched. The rim is low on the superior part 

 of the proximal extremity, and is separated from the articular cotylus by a 

 concave subvertical surface, wider than long. The basal tendinous insertion 

 is subdiscoid and flat, with a lateral projecting rim, which is pierced at the base 

 by the arterial foramina. The general form of the phalange is more com- 

 pressed than in Mylodon harlani. Its superior middle line is broadly rounded, 

 and continues nearly uniform to the apex. One side is subregularly convex; 

 the other is divided into three planes. The middle one of these is flat, and ter- 

 minates in a short lateral ridge which extends to the apex. The superior plane 

 becomes somewhat concave near the apex, and the inferior gently convex" 

 (Cope, 1878, p. 385). This description applies well enough to the large ungual 

 phalanx of the fore foot in Mylodon gannani but does not indicate that the 

 two are identical. Nor has it been possible to compare Cope's specimen with 

 Paramylodon. Cope gives the following measurements (and in parentheses I 

 have added those of our specimen) : — 



Length of ungual phalanx 



Vertical proximal depth 



Vertical depth at middle of inferior tendinous tuberosity 



Vertical depth just beyond inferior tuberosity 



Width of proximal cotylus 



Width of unguis at middle 



Width of unguis near end 



