EEL 
scratching or digging. There cannot be a greater contrast than is 
presented between the short, broad, and flat phalange of the Glyp- 
todon, and the long and compressed claw-bone of the Megatherium. 
Of the posterior extremity of the Glyptodon, the tibia, which is 
anchylosed to the fibula, presents the structure characteristic of the 
tibia of the Armadillos; while in the Megathere the corresponding 
bones deviate widely in their proportions, and in the conformation of 
the distal articular surface from those of the Glyptodon. The con- 
formation of the astragalus, caleaneum, the cuboid, scaphoid, and 
internal cuneiform bones, also of the metatarsals of the three middle 
and largest toes, the three phalanges of the second and middle, and 
the distal phalanges of the third and fourth toes, were described in 
great minuteness, but it is not posstble to abridge the details. 
Mr. Owen, however, stated that when the bones of the hinder ex- 
tremity are arranged in their natural juxta-position, they present a 
foot of such singular proportions as to be without a parallel in the 
animal kingdom. The nearest approach to its broad, thick, short, and 
massive proportions is made by the skeleton of the fossorial extremity 
of the Mole ; but it is the fore foot only of this animal that can be com- 
pared in the compressed figure of the metacarpals and proximal and 
middle phalanges with the singular hind-foot of the Glyptodon. The 
hind foot of the Mole resembles in the lengthened metatarsal and pha- 
langeal bones that of the existing Armadillos, and the generality of 
quadrupeds. ‘The true structure of the hind foot of the Megatherium 
is not known, but in the terminal phalanges it differs most widely 
from those of the Glyptodon. In the former, the compressed length- 
ened shape is as extreme in the claw-bones as, in the latter, is the 
depressed, shortened figure. In the Glyptodon, the hind foot, like 
the fore, appears to be expressly modified to form a base to a column 
destined to support an enormous superincumbent weight; while in 
the Megatherium the toes were free to be developed into long and 
compressed claws, such as form the compensating weapons of de- 
fence of the hair-clad Sloths and Ant-eaters. The ungueal phalanges 
of the Armadillos, in their shorter, broader, and flatter form, make a 
‘much nearer approach to those of the Glyptodon ; and it may be 
readily admitted that the hind foot of the Glyptodon is an extreme 
modification of the same general plan of structure as that on which 
the foot of the Armadillo is constructed; but if the differences in 
the tarsal bones (described in the paper) exceed those which are 
traceable between one species of Armadillo and another, a fortiori, the 
antero-posterior compression of the metatarsals and phalanges, and 
the total suppression in those of the ginglymoid trochlear articula- 
tions are indicative of a difference of general habits, as great as is 
usually observed in animals of distinct but nearly-allied genera. Thus 
both the dental modifications and the locomotive organs prove that 
the Glyptodon cannot be called an Armadillo without making use of 
an exaggerated expression ; still less can it be considered a species 
of Megatherium ; but it offers the type of a distinct genus, which is 
much more nearly allied to the Dasypodoid than to the Megatherioid 
families of Edentata. For this genus Mr. Owen had proposed a name 
