368 R. S. Lull — Pleistocene Ground Sloth, 



Dimensions. 





Texas Mylo- 









don 

 Cat. No. 



Oregon 

 cast 



Eatios 





10266 









nini 



mm 





Length over all . _ 



375* 



406 



108 



Humeral facet, length, inner 









part 



101 



115 



114- 



Humeral facet, breadth 



108 



123 



114 



Shaft, least thickness 



32'5 



45 



138 





Av. 118 



* Estimated. 



It will be seen that the average of the ratios of ulnae and 

 humeri is exactly the same, 118, in each case. 



Manus. — The hand is represented by two scaphoids, a right 

 and a left, a right magnum, a left metacarpal IY, and two 

 unguals, both presumably of digit III of the left hand. 



Scaphoid. — The scaphoid preserved apparently articulates 

 with the radius already described, No. 10265, in such a way as 

 to accentuate the marked flexibility of the wrist, as the articula- 

 tions are full curved and of ample extent. The bone is roughly 

 triangular when viewed from above, with a rounded antero- 

 internal angle and a deeply concave postero-external side. Three- 

 quarters of the superior surface is articular and is convex in 

 both dimensions in its outer part, becoming concave first along 

 the transverse diameter and then in all directions in the broadly 

 expanded inner portion. The anterior aspect of the bone is 

 continuous with the outer face and the latter bears a rather 

 long, narrow lunar facet which is continuous with that of the 

 upper aspect though demarcated by a pronounced angle. The 

 lower margin bears two deeply rounded bays, the limits re- 

 spectively of the magnum and trapezoid facets. Except for the 

 facets the entire surface of the bone is highly rugose. Pos- 

 teriorly the bone is prolonged into a compressed angle bearing 

 on its external face a sub-circular facet with which articulated 

 the metacarpal of the tirst digit. When the bone is held with 

 its superior face horizontal, this facet nearly coincides with the 

 vertical antero-posterior plane. In its proper orientation, how- 

 ever, as indicated by the distal end of the radius, the upper 

 surface of the scaphoid is inclined sharply downward and out- 

 ward, which inclines the metacarpal facet obliquely downward 

 in such a manner as to make the articulation feasible. 



