320 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 9, 
On applying a fragment of the back of a vertebra in Mr. Fox’s col- 
lection (woodcut), we found that when the postzygapophyses rested 
on the preezygapophyses, the posterior vertical median plate fitted into 
the notch between the latter, its sides articulating with the subtri- 
angular articular surfaces of these. 
Fig. 1.—Reduced outline of a camera-drawing of a fragment of the 
back of a similar vertebra in Mr. Fox's collection. 
— . 
w psz 
ns'. Posterior pillars of composite neural spine. 
psé. Postzygapophyses. 
w. Vertical median wedge-plate descending from junction of psz to 
crown of neural canal. 
vr. Vertical mesial ridge, for interspinous ligament. 
vp. Thin vertical plate descending to platform. 
plt. Horizontal platform. 
The neural spine consists of an anterior pair of pillars (now about 
7 inches long) which rise from the crown of the neural arch imme- 
diately behind the preezygapophyses (ns), and of a posterior pair of 
stouter pillars (ns’) which ascend from immediately above the post- 
zygapophyses. The two front and the two posterior pillars are 
joined by a thin lamina; and other thin plates pass between the 
front and back pair. The plate which unites the two front pillars 
is indented; so that these pillars are separated by a deep retiring 
angle, open forwards ; while the plate which connects the two pos- 
terior pillars developes a vertical median crest (v7) projecting back- 
wards, and haying a strong, rough edge, as if for the attachment 
of an interspinous ligament. Below, the crest contracts, and ends 
in a deep hollow just above the union of the inner borders of the 
postzygapophyses. 
