186 EDENTATA 
basin of the Rio de la Plata. Dr. Leidy has described, from similar 
formations in Georgia and South Carolina, bones of a closely allied 
species, about one-fourth smaller, which he has named MZ. mirabile. 
Three other South American species have been described; but JZ. 
lawrillardi, of Lund, founded upon remains found in Brazil, has 
been made the type of the genus Ocnopus. 
The following description will apply especially to the best-known 
South American form, Megatherium americanum. In size it exceeded 
any existing land animal except the elephant, to which it was 
inferior only in consequence of the comparative shortness of its 
limbs ; for in length and bulk of body it was its equal, if not 
Fic. 62.—Skeleton of Megatherium, from the specimen in the Museum of the Royal College 
of Surgeons. x 34. 
superior. The full length of a mounted skeleton (Fig. 62), from 
the fore part of the head to the end of the tail, is 18 feet, of which 
the tail occupies 5 feet. The head, which is small for the size of 
the animal, presents a general resemblance to that of the Sloth ; 
the anterior part of the mouth is, however, more elongated, and the 
jugal bone, though branched posteriorly in the same way as that of 
the Sloth, meets the zygomatic process of the squamosal, thus 
completing the arch. The lower jaw has the middle part of its 
horizontal ramus curiously deepened, so as to admit of im- 
plantation of the very long-rooted teeth, the peculiar structure 
of which has been already described. A skull recently discovered 
shows that, instead of the wide gap between the extremity of 
the nasals and the premaxille exhibited in Fig. 62, there was 
a prenasal bone, towards which a process extended upwards and 
