688 SHUFELDT—OSTEOLOGY OF THE STRIGES. [Dee. 7, 
dorsal vertebrze number five ; the anterior one articulates with the last 
cervical and the last dorsal with the first sacral. Although the 
dorsals of this bird fit very snugly to each other, it requires no 
further masceration to separate them from one another than it does 
to remove the ribs from their attachments. This close interlock- 
ing, however, greatly diminishes the movement of this division of 
the spinal column, bestowing upon it a rigidity only exceeded by 
the anchylosed vertebrz 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 hav- 
ing a firm hold upon the remainder of the vertebree below. Taken 
separately, the last is the smallest, the fourth 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 backward and 
forward, thickened and wedged into each other. This wedging is 
performed in the following manner: The posterior extremity of the 
crest forming the summit of the neural spine of the first dorsal 
divides and receives the anterior extremity of the crest of the 
second, Thissame arrangement exists between the second and third, 
and at the summit between the third and 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 joining is feebly attempted between the fourth 
and last. 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 vertebrz from above in the articulated skeleton, 
we observe the spinous crest already described ; we are struck with 
the regularity with which the postzygapophyses overlap and adjust 
themselves to the prezygapophyses from before backward, the 
facets of the former facing downward and outward, the opposed 
surfaces of the latter facing upward and inward. The transverse 
processes are horizontally compressed and rather broad ; the neural 
spines jut from them at right angles from points about their 
middles. There is an inclination for the latter to be directed 
slightly backward as we near the sacrum. The diapophysis of the 
