602 LAND MAMMALS IN THE WESTERN HEMISPHERE 



abruptly truncated, the nasal opening very large. The lower 

 jaw had a straight inferior border, a short, very wide and shovel- 

 shaped symphysis and square chin. Nothing indicates a pro- 

 boscis, and the head must have been very different from that 

 of '\ Megatherium. 



Within the family of the fmylodonts there was some variety 

 in the dentition and more in the shape of the skull. In fLes- 

 todon, for example, the first tooth in each jaw was a large, 

 sharp-pointed tusk, the muzzle was greatly broadened, and the 

 whole animal was larger. ^Scelidotherium, the smallest 

 Pleistocene member of the family, had a much narrower and 

 more elongate skull than the others. In \Glossotherium, 

 which also had an elongate skull, there was an arched bony 

 bridge connecting the anterior end of the nasal bones with the 

 premaxillaries and dividing the nasal opening into two parts. 



The neck, body and tail of ^Mylodon did not differ mate- 

 rially from those of \ Megatherium, except in being smaller and 

 less massive. The fore limb was relatively somewhat shorter 

 and much stouter, but otherwise similar ; the humerus had no 

 epicondylar foramen and the femur no third trochanter ; the 

 tibia and fibula were separate. The manus had five digits, 

 Nos. I, II and III carrying claws, that of III being especially 

 large ; IV and V had no claws and the outer edge of the manus 

 rested on the ground in walking, the sole turned inward. The 

 pes had lost the first digit, the second and third had claws, but 

 not the fourth and fifth ; the weight rested on the outer edge. 



The skin is definitely known from large pieces belonging 

 to the allied genus \Grypotherium, found in a cavern near 

 Last Hope Inlet, Patagonia, where it had been preserved by 

 burial in dry dust. Externally, the skin was thickly covered 

 with coarse hair and in the deeper layers was a continuous 

 armour of small ossicles, which were close set and in the Last 

 Hope specimens show like a cobble-stone pavement on the 

 inner side of the skin, the innermost layers of which have been 

 destroyed ; in life, these small bones were not visible. Simi- 



