1 6 A Remarkable Ground Sloth 



entirely on the outer margin and mainly on the fifth metatarsal, which is peculiarly 

 shaped and must have been protected from impact by a thick, shock-absorbing cushion 

 which is not preserved. The foot agrees with Stock's description in that the ves- 

 tigial metatarsal I has fused with the entocuneiform, the remainder of the hallux 

 having entirely disappeared. Stock says that metatarsal IV "supported apparently 

 such rudimentary elements as are present in the corresponding digit of Mylodon." As 

 a matter of fact digit I V is complete and bore a claw which, however, is smaller than 

 that of digit 1 1 and much smaller than that borne on digit III. In the Yale specimen 

 the entire digit IV in each foot is flexed sharply toward 1 1 1, the axis being about 50° 

 out of alignment with that of the metatarsal (see Plate VI, A, B). This deflection is 

 apparently normal but may be somewhat exaggerated, due to tissue shrinkage, as the 

 three claws are now in contact at their tip. The digits are enclosed in a common in- 

 tegument to near the base of the second claw but involving a portion of the third and 

 fourth claws. 



Stock says of metatarsal V that a facet at the distal end indicates the presence of 

 a nodule. The Yale specimen shows not only one but two bones representing the first 

 and second phalanges. The second of these is rounded at the tip and bore no facet. The 

 appearance of the digit is quite similar to that of the fifth digit of the right manus (see 

 above, p. 13), which I considered as probably accidental, as a claw is borne on the cor- 

 responding digit of the left manus. In view of the condition of the pes, however, it is 

 possible that there was no accident to the right hand but a normal tendency toward 

 the reduction of the digit, manifest in the right manus but not in the left. 



There is quite a heavy pad on the base of each claw, somewhat larger in the pes 

 than in the manus. 



MEASUREMENTS OF PES 



Length of foot, on chord to middle claw 

 Length of foot, on curve 



* The right pes is flexed more than the left. 



EXOSKELETON 



Hide ( Plate VII I ). — Five areas of hide are preserved, on top of the head, on the 

 right scapula, over three ribs on the right side in the wake of the scapula, on the right 

 ilium, and at the base of the tail. That over the ilium averages 5 mm. thick. There is 

 no trace of dermal ossicles or other armor. Hair is indicated on most of the patches of 

 hide, but only on the ilium is it well preserved. 



Hair (Plate VIII). — This is pale yellow in color, subcylindrical, smooth, fairly 

 coarse and straight, about 45 mm. in average length on the rump. It must have formed 



