GIANT GROUND SLOTHS — GAZIN 



349 



ried its weight on the "knuckles" with the distal extremities of the 

 metacarpals resting on the ground and the palm and the claws turned 

 inward (see figure at right, pi. 1). The hindfoot was turned so that 

 in locomotion the weight was carried along the outer side of the foot 

 with the plantar surface and claw of each likewise turned inward (see 

 figure at left, pi. 1) . The length of the hindfoot from the bony core of 

 the claw to the heel in one animal measured 36 inches (figs. 4 and 5), 

 possibly the greatest for any kind of land animal. 



Figure 1. — Skull (U.S.N.M. No. 20872) associated with large skeleton of Eremotherium 

 rusconii (Schaub) from El Hatillo shown in plate 2, and lower jaws of skull returned to 

 Panama. Note fantastic projections of the zygomatic arch and extremely low position of 

 orbital rim indicating location of eye about on level with teeth. About J^ natural size. 



Detailed comparison of the skeletal remains of Eremotherium with 

 those of the earlier known Megatherium of Argentina has brought out 

 several features that indicate clearly that Eremotherium is a distinct 

 genus, characteristic, as noted by Hoffstetter, of the more tropical 

 regions of the Americas. In comparing the skulls one notes that the 

 palate and lower jaws did not extend so far forward from the position 

 of the teeth and that the eyes or orbital margins were noticeably lower 

 than in Megatherium, about on a level with the grinding surface of 

 the upper teeth (fig. 1) . Also the lower jaws, though deep beneath the 

 teeth, were not nearly so much so as in Megatherium and the longi- 

 tudinal profile of the lower margin was not nearly so convex down- 

 ward. A more detailed comparison of the skulls has been made by 

 Hoffstetter, and certain characteristics of the appendicular skeleton 

 were noted by him, such as the form of the femur. To this may be 

 added that the articulating surface on the head of the femur, for the 

 acetabulum or hip socket, faces more proximally with a more pro- 

 nounced saddle between the head and greater trochanter. Moreover, 

 Owen's (1860, pi. 38) illustration of the femur of Megatherium shows 



