1900. ] SHUFELDT—OSTEOLOGY OF THE STRIGES. 695 
horizontal plane ; posterior to this line there is a decline, which 
declination is accepted also by the innominate bones ; this gives the 
entire pelvis a shape that seems to be characteristic of a majority of 
both the diurnal and nocturnal Rapiores. The ‘ ilio-neural’’ canals 
here present open but small apertures posteriorly at about the point 
where the ilia commence to diverge, passing obliquely downward 
and forward ; their anterior openings are large enough to allow a 
view of their internal walls. The neural spine that divides them 
throughout is compressed from side to side; the ilia which form 
their outer boundaries are convex ; the neuro-spinal crest forms the 
roof, the basal surface being deficient, formed merely by the spine- 
like di- and parapophyses of the vertebrz and the confluent neural 
arches. Now, a line drawn mesially on the centra below, from 
the first centrum to the last, gradually rises until opposite the 
anterior borders of the ischiadic foramina, then curves rather 
abruptly downward to its termination. The centra of the first 
two or three vertebrae are compressed from side to side to such 
an extent as to cause them to appear wedge-shaped, the com- 
mon apex or edge being below; after that, however, they rapidly 
broaden, become compressed vertically and more cellular in 
structure. They are very broad from the fourth to the ninth, inclu- 
sive, then as rapidly become contracted as they approach the 
coccyx. Minute but numerous pneumatic foramina are seen at or 
near the usual localities. The largest foramina for the exit of the 
roots of any pair of sacral nerves is generally in the fifth vertebra ; 
they decrease in size as they leave them either way. In the young 
only the last few of these foramina are double; they are all double 
in the adult, and placed one above another, a pair on the side of 
each centrum at their posterior borders. The tranverse processes 
of the anterior five sacral vertebre are thrown out against the inter- 
nal surfaces of the ilia, to which they are firmly attached, and act 
as braces to hold the engaged bones together. The parapophyses 
of the first form facets for articulation with the sacral ribs; the sec- 
ond and third have none; in the fourth and fifth they also act as 
braces in the manner above described, joining the ilia just before 
their divergence commences. Reliance seems to have been placed 
entirely in the completeness of the sacro-iliac union in the last ver- 
tebrz, for the apophysial struts terminate in that portion of the 
pelvic vault formed by the sacrum itself, except in the last two ver- 
tebre, where the parapophyses abut against the iliac borders. The 
