68 PROFESSOR HTJXLET OX THE OSTEOLOGY OE THE GENUS GLYPTODON. 
the curve of the centra posteriorly, to 5 inches. The spinous process of the penultimate 
coccygeal vertebra is very thick, but it is broken short off. It was probably not less than 
4 inches high, and afforded a middle point of support for the dermal shield between the 
ischial protuberances (Plate IX. fig. 1). 
The sides of the two anterior sacral vertebrae and the corresponding part of the sacral 
crest are anchylosed with the inner edges of the iliac bones, so that only a narrow oval 
space, left between these parts, near the upper edge of the crest, and the small canals 
above mentioned, allow of any communication between the region in front of, and that 
behind the ilia. 
Behind this point the vertebrae are devoid of transverse processes as far as the fourth 
from the end. But the antepenultimate had a long and slender transverse process on 
each side ; the penultimate possesses an equally long but much stouter process, and the 
last coccygeal vertebra has extremely thick processes of the same length. The enlarged 
distal ends of these processes unite with one another and with the inner surfaces of the 
ischia (Plate IX. figs. 1, 2, 4). 
Caudal Vertebra . — No caudal vertebrae existed among the remains of this specimen of 
Glyptodon. 
Of the Vertebral Column as a whole . — It appears from the foregoing description that 
the atlas of the Glyptodon was moveable upon the odontoid vertebra ; but that the latter 
was anchylosed with the third and fourth cervical vertebrae into one short bone, move- 
able upon the fifth cervical ; of the fifth and sixth cervical vertebrae no remains exist. 
The seventh cervical is anchylosed with the first and second dorsal into a single “ triver- 
tebral bone,” upon the front part of which the sixth cervical was certainly moveable ; 
while the hinder part of it freely articulates with the third dorsal, so that the bone 
was capable of motion through a certain vertical arc. 
Beyond this point, as far as the fourteenth dorso-lumbar vertebra, the vertebrae are so 
connected by complete, or partial, anchylosis, that it is impossible any motion should 
have taken place between them ; and it is probable, though not so certain, that the 
fifteenth dorso-lumbar vertebra was similarly fixed. 
Between this and the two hindermost lumbar vertebrae, which are completely anchy- 
losed together and with the sacral vertebrae, there is a hiatus, but the condition of the 
two latter is not such as to lead to the supposition that the intermediate vertebrae were 
less firmly united than they. 
The free cervical portion of the vertebral column must have been remarkably short, 
probably not exceeding 8 inches in length, and the cervical vertebrae were most likely 
arranged in a nearly straight line. 
The trivertebral bone and the thirteen following dorso-lumbar vertebrae, when articu- 
lated together, form one great curve, concave downwards or towards the visceral cavity, 
the curve being much sharper in the anterior than in the posterior part of the column. 
Measured along its curvature, this part of the vertebral column is about 35 inches long. 
At the anterior part of the sacral region the lumbar curve passes into the straight 
