294 



University of California Publications in Geology 



[Vol. 12 



MEGALONYX?, sp. 



Material. — The phalanx of a ground-sloth, Univ. Calif. Coll. Vert. Pal. no. 

 23372 (figs. Id and le), Univ. Calif, loc. 3243. 



Measurements 



No. 23372 



Greatest anteroposterior length 54.5 mm. 



Greatest dorsoventral depth of proximal end 36 



Greatest transverse thickness at middle 33.5 



The specimen (fig. 1) is of nearly bilateral symmetry; the proximal 

 articulation consists of two vertical concavities separated by a median 

 ridge, the upper and lower extremities of which are of nearly equal 



Id le 



Figs. Id and le. Megalonyx? , sp. Second phalanx, no. 23372, X %. Fig. Id, 

 lateral view; fig. le, distal view. Bautista beds, California. 



size and production ; the convex borders of the distal trochlea describe 

 approximately two-thirds of a circle, the groove of the trochlea is 

 very deep. 



Remains of both the genera Nothrotherium and Mcgalonyx occur 

 in the Pleistocene of Raneho La Brea and in the cave deposits of 

 northern California. Dr. Chester Stock, who kindly has examined 

 the specimen, states that it possibly represents a phalanx of a small 

 megalonychid form. The Bautista specimen is short and slender com- 

 pared to a phalanx from Hawver Cave which has been tentatively 

 referred to Megalony.r. It resembles somewhat phalanx 2, digit 2 of 

 the manus of Mylodon from Rancho La Brea but is smaller. 



