8(j Observations on the Natural History 
has a peculiar form, possessing a dentiform process and articu- 
lating surfaces, on which the condyles of the occiput rest. All 
the others consist of a body, contracted in the middle like an 
hour-glass, and, except towards the extremity of the tail, each 
^vertebra is furnished with four articulating apophyses , or pro- 
cesses, two anterior, and two posterior. The two anterior pro- 
cesses of each vertebra are covered by the posterior ones of the 
vertebra above it ; and its two posterior ones cover, in turn, the 
anterior processes of the vertebra below : so that, viewed from 
above, the vertebrae seem to be placed in the manner of tiles. 
Beside these processes, all the vertebrae, except the atlas 
and some of the caudal , have two transverse processes, which 
vary a little in form in different parts of the spine. In the third 
vertebra, these processes, which in the bone above were entire, 
separate into two portions of unequal length, and to the shorter 
portion is attached the rudiment of a rib. The same structure 
is continued downward to the ninth vertebra, where this parti- 
tion of the process ceases. Below the ninth vertebra, these trans- 
verse processes are formed of two thin laminae united together, 
and stand out from the body of the bone, like the unfledged 
wings of a young bird. Gradually these laminae diminish and 
disappear, so that about the third or fourth caudal vertebra 
they exhibit only a simple spine; and this spine, continually be- 
coming smaller, vanishes also about the tenth caudal vertebra. 
In addition to these transverse processes, the vertebrae of these 
animals have also their spinous processes, which spring from the 
extreme posterior and superior border of each vertebra. Beside 
having the dorsal spinous processes, the caudal vertebrae are fur- 
nished with two other spinous processes on the opposite surface of 
the bone, and which, from their position, may be named ventral. 
These spring from the roots of the transverse processes on each 
side, and proceeding in a parallel course, very soon unite, and 
form a canal, through which the bloodvessels, that are distri- 
buted to the tail, are continued. By the gradual diminution of 
the processes, this canal is lost before reaching the extremity of 
the tail. 
So much for the bones of the cranium and spine. Of the ske- 
leton there still remain the bones of the four extremities, the 
pelvis, and the shoulder. But it would be tiresome and useless. 
