“604 GEOLOGICAL SURVEY OF THE TERRITORIES. 
directed forwards and downwards. There are three on each of the last 
two vertebrae, each having an independent root, the two lateral ones 
directed downwards, forwards, and outwards, with characteristics similar 
to the one in the median line. Several pneumatic and nutrient foramina 
perforate each cervical vertebrae at various points, except in the axis 
and atlas, where, after diligent search, aided by the lens, we have sig- 
nally failed to discover them. 
Dorsal vertebre ; vertebral and sternal ribs ; sternum.—The dorsal ver- 
tebre number five; the anterior one articulates with the last cervical 
and the last dorsal with the first sacral. Although the dorsals of this 
bid fit very snugly io each other, it requires no further maceration to _ 
separate them from one another than it does to remove the ribs from 
their attachments. This close interlocking, however, greatly diminishes 
the movement of this division of the spinal column, bestowing upon it a 
rigidity only exceeded by the anchylosed vertebra of the sacrum; yet, 
it must be understood, they do enjoy, in this Owl, a considerable degree 
of movement, especially laterally. The neural spines have here attained 
their maximum development, forming, when taken together, an elevated 
and compressed median crest, with a thickened summit, and having a 
firm hold upon the remainder of the vertebre below. Taken separately, 
the last is the smallest, the fourth next, the first next, and the second 
and third the largest. Their anterior and posterior borders are concave, 
allowing, when articulated, spindle-shaped apertures to exist among 
them, while their summits are produced backwards and forwards, thick- 
ened, and wedged into each other. This wedging is performed in the 
following manner: The posterior extremity of the crest forming the sum- 
mit of the neural spine of the first dorsal divides and receives the an- 
terior extremity of the crest of the second. This same arrangement ex- 
ists between the second and third, and at the summit between the third 
and fourth, but the fourth immediately below the junction also divides 
for a little distance and receives the edge of the posterior rim of the 
third, just beneath the union of the crests. This latter method of join- 
_ ing is feebly attempted between the fourth and last. (See Pl. 1.) The © 
neural canal is nearly cylindrical in the dorsal region, its calibre being 
less at the sacral extremity, and rather compressed from side to side, as 
are the centra as we approach that end, each one being a little more so 
than its neighbor beyond. Viewing these five vertebra from above in 
' the articulated skeleton, we observe the spinous crest already described ; 
we are struck with the regularity with which the postzy gapophyses over- 
lap and adjust themselves to the prezygapophyses from before back- 
wards, like the scales in some fishes, the facets of the former facing 
downwards and outwards, the opposed surfaces of the latter facing up- 
wards and inwards. The neurapophyses are horizontally compressed 
aud rather broad; the diapophyses jut from them at right angles from 
points about their middles. There is an inclination for the latter to 
be directed slightly backwards as we near the sacrum. The diapophy- 
sis of the first dorsal is the shortest and stoutest, that of the last the most 
delicately constructed. Superiorly, these processes support metapophy- 
sial ridges at their extreme outer borders. These ridges on the diapophy- 
ses of the first dorsal are the largest, rounded at both ends, extending 
a little both backwards and forwards, but far from touching the ridge 
either in front or behind them. The metapophysials of the last dorsal 
are smaller, sharp, styliform, and project only forwards, though they 
do not by any means touch the diapophyses in front of them. On 
the intermediate vertebra they change gradually between these two 
extremes, but in no instance meet the diapophyses of the vertebra be- 
