DR. GUNTHER ON THE ANATOMY OE HATTERIA. 
605 
2 sacral (26, 27). 
36 caudal (28-63). 
As regards the first five vertebrae (fig. 17), Professor Owen (l. c.) has given so detailed 
a description of them, that 1 may be allowed to quote it in full. 
“ The atlas consists chiefly of the hypapophysis and neurapophyses ; the former is in 
the form of a transverse arched bar, concave upwards, with the anterior border cut 
obliquely to receive the under part of the occipital condyle; the posterior border is 
convex vertically, and adapted to the transverse trochlear groove in the fore part of 
the odontoid process ; the neurapophyses have a small articular surface at the fore part 
of their base for the occipital condyle, and a second at their inner and back part for their 
proper centrum, the odontoid process. They are expanded superiorly, develope a small 
posterior zygapophysis, exterior to which is a tubercle ; and they come in contact, but 
do not coalesce, above the neural canal. The odontoid process [fig. 18] has coalesced 
with the body of the axis, which it equals in height and exceeds in breadth ; it is convex 
from side to side, concave vertically at its lower half, having, as it were, a channel scooped 
out from side to side ; this kind of joint will allow of great extent and freedom of mo- 
tion of the atlas with the head from side to side ; whilst the vertical movements would 
be restricted. The neurapophyses of the axis have coalesced with the centrum below, 
and with each other above, where they develope a strong ridge or spine, which is most 
produced in the antero-posterior direction. An autogenous hypapophysis [fig 17, e] is 
wedged into the inferior insterspace between the centrum of the axis and the third vertebra. 
The centrum and neurapophyses of the third vertebra have coalesced ; a short diapophysis 
projects from the line of union. The anterior and posterior zygapophyses form the 
angles of the broad base of the neural spine ; this spine is of moderate length, thick and 
trihedral. There is a small wedge-shaped hypapophysis beneath the interspace of the 
third and fourth vertebrae. The fourth vertebra has a short pleurapophysis on each side, 
with a bifurcate proximal end articulated by a broad tubercle to the diapophysis and by 
a slender neck and head to a rudimental parapophysis ; but this is very feebly marked otf 
from the diapophysis. In the fifth vertebra the parapophysis and diapophysis form 
together an oblique ridge, chiefly extended vertically, and to which the expanded head 
of the pleurapophysis articulates by a single surface. There is a wedge-shaped hypapo- 
physis at the interspace of the fourth and fifth vertebras.” 
This description agrees in every point with the three skeletons examined by myself, 
except that, in one example, the pleurapophysis of the fourth vertebra is not bifurcate, 
the lower branch being replaced by a ligament, and no trace of a parapophysis can be 
distinguished. 
The hindmost autogenous hypapophysis (fig. 17, e ') corresponds to the seventh and 
eighth vertebrae. The dorsal vertebrae differ scarcely from the middle and posterior 
cervical ; the zygapophyses are more distant from one another ; and the oblique ridge 
formed by coalesced diapophysis and parapophysis is less prominent, receding nearly to 
the level of the centrum, on the hinder dorsal vertebrae. The centrum, the lower half 
4 N 2 
