NOTICE OB’ THE MEGAEHERIUM. 
9 
of a persistent formative capsule meets well the requirements of the dental apparatus of an 
animal whose life extended, as there is reason to believe, over more than a century.* 
The Spinal column presents a character of great strength and firmness of articulations. 
It is composed of 7 cervical, 16 dorsal, 3 lumbar, 5 sacral, and 18 caudal vertebral, — the 
entire length being 15? feet. At the extremities the body of the vertebrae is round or oval ; 
between the pelvis and neck it is trihedral. The sacral vertebrae are anchylosed to each 
other and to the pelvis, as in other quadruped Mammals. The neural canal is here a foot in 
circumference, and its very unusual size is sustained throughout the entire length of the 
column. There are sixteen pairs of ribs, of which eight articulate with the sternum, by 
means of completely ossified cartilages or haemapophyses. The circumference of the skeleton 
at the eighth rib is ten feet, behind this the free ribs bend rapidly outward and upward, so 
that in the abdominal region their distal extremities are nearly as high as the crest of the iliac 
expansions of the pelvis. 
The Anterior Extremities manifest all the main perfections of brachial structure to be 
seen in the Mammalian class. Their vast proportions, moreover, indicate enormous strength 
and show that the limbs had a further office than simply to support the body. In no other 
respect does the Megatherium differ more strikingly from existing quadrupeds of correspond- 
ing bulk. The scapula is a vast expanse of bone, two and a half feet in its greatest length? 
* An analagous disposition of hard and soft vertical layers occurs on a still larger scale in the teeth of the 
Elephant, hut in this gigantic leaf-feeding quadruped we find a different plan of repairing the Wear ; new teeth 
being supplied from below to replace the old ones which fall out, 
Owen, in speaking of the character of the Megatheroid tooth (Zoology of the Beagle, page 33), says : 
“ Besides the relation to food requiring much comminution, which teeth with persistent bulbs hear, they are also 
connected with the longevity of the individual . The term of life in a herbivorous animal, with grinders of tem- 
porary growth, is of course dependent on the duration of these essential aids to nutrition. Thus a sheep wears 
down its grinders in twelve years, and its life is consequently limited to about that period.” 
