334 R. S. Lull — Pleistocene Ground Sloth, 



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 terminates 

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

 superior plane becomes somewhat concave near the apex, and 

 the inferior gently convex. 



" The proximal phalanges have the form usual in the genus. 

 They are rather short, and with the trochlear, tongues and 

 grooves strongly marked. The proximal extremities are 

 especially expanded in the vertical direction. 



" In size, this species equalled the M. harlani or the 

 Megalonyx jeffersonii. 



" From the Pliocene of Oregon." 



To this species Cope * also refers provisionally a specimen 

 from Rock Creek, Texas, as follows : 



" Mylodon f sodalis Cope. — The distal part of a femur, lack- 

 ing part of the internal condyle and adjacent epicondyle, repre- 

 sents a gigantic species of Mylodon. At present it is not 

 possible to determine exactly its specific relations, but its asso- 

 ciation with the species of the Equus fauna renders it possible 

 that it is the animal which has been found associated with the 

 same fauna in Oregon, and which I have named as above. 

 The measurements of the part preserved are about equal to 

 those of the M. robustus, Owen, from Argentina. The trans- 

 verse extent of the condyle is about 210 mm (restored), of which 

 the popliteal fossa is about 60 mm . 



" Since the species was described, I have received from Mr. 

 George Duncan, of Paisley, Oregon, an imperfect symphysis 

 mandibuli from near the original source of the M. sodalis, 

 which presents characters appropriate to that genus and 

 species." 



Mylodon renidens Cope. 



Cope's original description! reads as follows : 



" This species is founded on a right maxillary bone, which 

 contains all but the first molar tooth. This tooth is represented 

 by an alveolus broken anteriorly, and the free portions of the 

 crowns of the second and third molars are broken off. The 

 crowns of the fourth and fifth molars are perfect. Associated 

 with this specimen are the following, which probably belong 

 to the same species : The posterior three molar teeth of the 

 inferior series ; a superior first molar in place in the anterior 

 part of a right maxillary bone. 



u The superior and inferior series referred to are consider- 

 ably smaller than the corresponding parts of the M. harlanii, 



*Cope, E. D., Geol. Surv. Texas, 4th Ann. Rept., p. 78, 1893. 

 fCope, E. D., Proc. Amer. Philos. Soc, vol. xxxiv, p. 460, pi. 10, fig. 3, 

 pi. 11, figs. 5, 6, 1896. 



