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 
mandibuli 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 garmani 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 185 mm. (177) 
Vertical proximal depth 58 (59) 
Vertical depth at middle of inferior tendinous tuberosity 55 (61) 
Vertical depth just beyond inferior tuberosity 44 (37) 
Width of proximal cotylus 52 (37) 
Width of unguis at middle 33 (30) 
Width of unguis near end 20 (15 +) 
