12 



A Remarkable Ground Sloth 



APPENDICULAR SKELETON 



Clavicle. — The clavicles in Stock's description agree with ours, except that the 

 former are decidedly smaller, save in one dimension,* a rather remarkable feature, 

 the reverse of what occurs in nearly every other element of the skeleton. 



CLAVICULAR MEASUREMENTS 



Greatest length 

 ♦Greatest width sternal end 

 Greatest thickness sternal end 

 Width mid-shaft 

 Thickness mid-shaft 



Scapula. — The scapulae correspond closely in general outline and as usual are 

 of smaller size than are those of the Rancho la Brea, which makes the discrepancy in 

 the adjacent clavicles all the more remarkable. The explanation probably is that the 

 clavicles studied by Stock belonged to a very immature individual not more than four- 

 fifths the size of the Yale specimen, which in turn is about nine-tenths the optimum. 



SCAPULAR MEASUREMENTS 



Rancho la Brea 

 Extremes Mean 



Length glenoid cavity to suprascapular border, 



along the spine 

 Greatest width of blade at suprascapular border 



236.0-246.0 

 249.6-272.7 



237.6 



257-5 



Yale 

 Y.P.M. 13198 



222.0 

 225.0 



Humerus (Plate II). — Here again the principal differences between the Yale 

 humeri and those of the Rancho la Brea lie in an apparent age distinction in that the 

 latter are much more rugged and robust, correlated with greater muscular develop- 

 ment. 



HUMERAL MEASUREMENTS 



Greatest length 

 Width at proximal tuberosities 

 Width at mid-shaft 

 Greatest width distal end 



Rancho la Brea 

 No. 1874 R-i 



432-4 

 106.2 



55-3 

 168.0 



Yale 



Y.P.M. 13198 



387.0 



94.2 



52-8 

 140.0 



