A Remarkable Ground Sloth 



15 



I have compared the femora of our animal with that of Morotherium gigas, 

 Y.P.M. 1 1898, Holotype. The latter is larger and more robust. It is also defective in 

 outline. There seems to be no generic distinction between the two, but whether this ele- 

 ment is sufficient to determine congeneric relationship, in which event Morotherium 

 would take precedence over Nothrotherium, I am not prepared to say, in view of the 

 inadequacy of the Morotherium type. There is in addition a fragment of humerus, but 

 the two elements are insufficient. 



FEMORAL MEASUREMENTS 



Greatest length from head 



Length from great trochanter 



Width obliquely from great trochanter 



Thickness of mid-shaft 



Least width of mid-shaft 



Greatest width, distal end 



Tibia. — Less ruggedness characterizes the Yale tibiae as compared with those of 

 the Rancho la Brea in conformity with comparative individual age. 



TIBIAL MEASUREMENTS 



Greatest length along mid-shaft 

 Greatest transverse width, proximal end 

 Greatest transverse width, distal end 

 Least width, mid-shaft 



RATIO TIBIA TO FEMUR 



N othrotherium shastense 

 Nothrotherium shastense 

 Ha-palofs longice-ps 



Rancho la Brea Y.P.M. 13198 Hafalofs 

 0.796: 1 



0.740: 1 



0.768: 1 



Pes (Pis. II, VI, VII). — In the Yale specimen the right pes is complete, while 

 the left lacks two phalanges of the vestigial digit V. 



Stock speaks of the foot posture as resting mainly on the outer side (italics mine). 

 The Yale specimen is held by ligaments so that the posture is established. The mor- 

 phological sole of the foot is perpendicular to the ground. Thus the weight is borne 



