588 
professor OWEN ON THE MEGATHERIUM. 
present to the zoologist, conversant only with living species, a singular exception in 
their dental characters to the rest of their class ; but there has been a time when 
this peculiar dentition was manifested under as various modifications as may now be 
traced in some of the more common dental types in existing orders of Mammalia.” 
Comparative Table of Dimensions of the Skull of Megathere, Mylodon, and 
SCELIDOTHERE. 
Megatherium 
Americanum. 
Mylodon 
robustus. 
Scelidotherium 
leptocephalum. 
Cranium. 
ft. 
iu. 
lin. 
ft. 
iu. 
lin. 
ft. 
in. 
lin. 
Length fiom the occipital condyles to the fore-end of the upper 
jaw 
2 
7 
0 
1 
6 
6 
1 
8 
4 
Length from the occipital condyles to the fore-part of the 
malar bone 
1 
8 
0 
1 
2 
0 
0 
11 
6 
Lengtli from the fore-part of the malar bone to the fore-end 
of the upper jaw 
0 
10 
6 
0 
5 
0 
0 
8 
8 
Breadth across the widest part of the zygomatic arches 
0 
10 
9 
0 
7 
0 
Least breadth at the interspace of those arches 
0 
6 
0 
0 
5 
4 
0 
3 
7 
Breadth of the fore-part of the nasal bones 
0 
4 
6 
0 
3 
3 
0 
2 
8 
Mandible. 
• 
Length 
2 
3 
0 
1 
3 
6 
1 
6 
6 
Breadth between the hinder ends (angles) of the rami 
0 
7 
0 
0 
6 
3 
0 
4 
7 
Breadth between the condyles 
0 
4 
0 
0 
4 
2 
0 
1 
8 
Breadth between the posterior sockets of the teeth 
0 
2 
3 
0 
2 
10 
0 
1 
6 
Breadth between the anterior sockets of the teeth 
0 
1 
9 
0 
4 
0 
0 
1 
8 
Breadth across the fore-part of the symphysis 
0 
4 
5 
0 
5 
4 
0 
2 
5 
Depth of ascending ramus from the upper part of the condyle 
1 
5 
0 
0 
5 
7 
0 
5 
8 
Depth of ascending ramus at the fore-part of the base of the 
coronoid process 
0 
9 
0 
0 
3 
7 
0 
3 
7 
Depth of horizontal ramus at the fore-part of the first socket.. 
0 
8 
0 
0 
3 
0 
0 
2 
7 
Length of the symphysis following the outer curve 
1 
1 
0 
0 
4 
3 
0 
7 
3 
Fore and aft extent of base of coronoid process 
0 
9 
0 
0 
3 
8 
0 
3 
9 
From the back part of the condyle to the end of the angular 
process 
0 
6 
0 
0 
3 
2 
0 
3 
6 
From the end of the angular process to the last socket 
0 
9 
7 
0 
6 
6 
0 
6 
5 
From the first socket to the anterior margin of the jaw 
0 
9 
0 
0 
3 
6 
0 
7 
10 
Extent of the alveolar series 
0 
9 
0 
0 
5 
4 
0 
4 
4 
Breadth of the condyle 
0 
3 
0 
0 
2 
6 
0 
1 
10 
