16 
NOTICE OF THE MEGATHERIUM. 
and the molars alone being present in the latter. The present representatives of the order are 
few in number, and but pigmies when compared with the huge creatures of allied structure 
which once dwelt upon the earth. Cuvier also showed that it was to the Tardigrade division 
of this group — the Sloth — that the Megatherium bore its closest affinities. These strange, 
uncouth animals now inhabit the forests of South America, where they spend their whole life- 
time in the trees, finding their entire food and sustenance in the leaves, which they strip from 
the highest and outermost branches. They are represented by but two species, the largest of 
which does not exceed two feet in length. No other fossil so exceeds in size its modern rep- 
resentative, as the Megatherium surpasses the pigmy remnant of the Tardigrade race. A 
Spanish critic made this objection to the place assigned to the Megatherium by Cuvier, that 
“ all the other Edentates could dance in his carcass.” The character of the teeth affords the 
crowning proof that it is to the diminutive arboreal Sloth that the great extinct quadruped 
has the closest affinity. The number of the teeth, their deep insertion, equable breadth and 
thickness, absence of fangs, deeply excavated base, inner structure, and unlimited growth, 
are characters common to both. The dental system here, in the order of Edentates, finds its 
lowest condition among Mammalia. The Sloths have the same anomalous shortness of face 
as the Megatherium, although, with them, the features is carried to a greater extent ; the 
cerebral cavity is masked by a similar development of air-cells ; and the alveoli of both jaws 
correspond in number, position and relative depth. 
The remarkable process hanging down from the zygomatic arch is a strange peculiarity 
which the Sloth alone among living animals retains, although it was possessed by a number 
of the Edentates (of two families), which are now found fossil. These similarities between 
the two heads are quite apparent when they are viewed side by side, as in the accompanying 
cuts. In the peculiar length of the premaxilliaries, the Megatherium differs from its living 
Skull of Megatherium Cuvieri, one-ninth natural size. Skull of Sloth (Bradypus tndactylus), natural size. 
congener, whose shorter tongue required no 'such support beneath. In the prolongation of 
the slender fore-part of the upper jaw, it approaches the Anteater, and, as a general rule, in 
those modifications of structure by which the Megatherium differs from the Sloth, it approxi- 
mates the Anteater, and, in a minor degree, the Orycterope and Armadillo. Ihus, in the num- 
ber and structure of the true vertebrae, the fossil Edentate departs from the Sloth, and agrees 
