SUPPLEMENT. 195 



Other Edentates could dance in his carcass." But that there is the closest 

 affinity between it and the diminutive arboreal Sloth, is now undeniable. 

 The number of the teeth, their deep insertion, equable breadth and thick- 

 ness, deeply excavated base, inner structure and unlimited growth, and the 

 absence of canines, are characters common to both. The part in which the 

 Megatherium least resembles the Sloth, is the tail; and, as a general rule, 

 in those modifications of structure in which it differs from its living ana- 

 logue, it approximates to the Anteater ; e. g. in the number and structure 

 of the true vertebr*. 



The head of the Megatherium is remarkable for its relatively small size, for 

 the extraordinary depth of the lower jaw, and for the great size of the zygo- 

 matic processes. The length of the skull is thirty inches ; three inches less 

 than that of the Asiatic Elephant. The formation of the muzzle indicates the 

 possession of a short proboscis. 



The spinal column consists of seven cervical, sixteen dorsal, three lumbar, 

 five sacral and eighteen caudal vertebrae, and measures fifteen feet in length, 

 or three feet more than the Elephant's. The circumference of the skeleton, 

 at the eighth rib is eleven feet. 



The Megatherium differs strikingly from existing quadrupeds of corres- 

 ponding bulk, in the vast proportions of its anterior extremities. Its clavicle, 

 fifteen inches long, is the longest known. The fore-leg bespeaks enormous 

 strength ; with the foot, it is seven feet and four inches in length. 



The posterior extremities are shorter than the anterior. The pelvis is the 

 largest bone in any land mammal, living or extinct ; it is upwards of five feet 

 broad. The rugged ilium and spinal crest ,, show that it was the centre of 

 muscular bundles of enormous power, which diverged to act upon the trunk, 

 the tail and the hind legs. These muscles, judging from the size of the spinal 

 cord, which in this region is four inches in diameter, must have been charac- 

 terized by the extreme energy of their vital contractibility. The acetabulum 

 is excavated in a very exceptional manner, its concavity facing directly down- 

 ward. This gave increased strength for sustaining vertical pressure at the 

 expense of rapid motion. 



The hind legs appear more like columns for support than organs for locomo- 

 tion, and, with the hind feet, are models of massive organic masonry. The 

 heel-bone alone has the extraordinary length of seventeen inches, and a cir- 

 cumference of twenty-eight inches. The monster walked, like the Anteater, 

 on the outside edge of its foot, on a marginal hoof-like callosity. The mid- 

 dle toe of the hind foot, and likewise the second, third and fourth digits 

 of the fore-foot, were armed with powerful claws. The magnitude of the 

 tail fills the observer with wonder ; when clothed with flesh, it must have 

 been more than six feet around at the greater end. With the hind legs, it 

 formed a tripod upon which the animal rested when obtaining its food. 



It would be interesting to know something of the daily life of the animal 

 whose colossal size was united to such strange anatomy. As the brain of the 

 Megatherium was less by nearly one-half than that of the Elephant, we infer 

 that he was a creature of fewer instincts. Nevertheless, his cotemporary 

 quadrupeds mu.st have acknowledged him as the head of the Animal King- 

 dom. To the tongue of a Giraffe and the proboscis of a Tapir, there was 

 added the power of rotating the bones of the fore-arm. These prehensile or- 

 gans were suited to a leaf-feeder. That the animal was not carniverous, is 

 settled by the structure of its molar teeth ; it lacks incisors ; therefore it was 



