SHUFELDT.] OSTEOLOGY OF THE CATHARTIDA. TUT 
of the spinal column, the number of the sacral segments as they occur 
in these Vultures. In every instance they form a thoroughly anchylosed 
“sacrum,” which in turn combines with the ossa innominata by perfect 
osseous amalgamation along the borders, more particularly anteriorly, 
for posteriorly or in the post: acetabular region the union with the ilia 
always is visible, and in some species allows a thin knife-blade to be 
inserted in the interstice by moderate . 
force (Pseudogryphus). The complete 
pneumaticity of the sacrum has already 
been cited and dwelt upon, and the 
facets for the sacral ribs, and how these 
ribs in some species unite with the ilia, 
has likewise been referred to in suffi- 
cient detail. 
Viewing this compound bone from 
above, we find that it is only in C. aura 
of the species we have before us where 
the ilia fail to meet in the median line, 
and thus conceal the common neural 
Spine of the pre-sacral vertebre (Plate 
X XI, fig. 117). In this Vulture quite 
an interspace exists between the ilia, 
8 millimeters at the narrowest place, 
which is filled in by the much com- 
pressed and very broad neural spine. 
Gyparchus makes the next nearest ap- \, 
preach to this condition. In all the ® 
others of the Cathartide the ilia meet 
for a greater or less distance mesiad, | 
and also slope downwards more rapidly ¢ 
from the line of junction, these bones | 
in the pre-acetabular region of Cathar- 
tes being quite in the horizontal plane 
anteriorly. Without exception, the 
neural spine of the first sacral vertebra 
juts out beyond the anterior borders of 
the ossa innominata, as the anterior 
moiety of the segment does below. 
Cathartes aura, from the arrangement 
just described, seems to be the only one 
of the family that has a posterior open- 
ing on either side for the “‘ilio-neural” 
canals, the close approximation of the Sacram of Catharista atra'a; viewed from 
ilia in others of the group precluding it. ehovex diteisize: 
The thoroughly united neural spines on this their superior aspect in 
this bird are also broad and flat from one extremity to the other, while 
in Catharista and Gyparchus such portions of them that show behind are 
slightly rounded from side to side, a condition well marked in the Condors. 
Referring the reader again to Plate X XI, figure 117, we observe how 
complete is the series, on either side, of interapophysial foramina in 
the Turkey Buzzard, and how an additional row of smaller ones exist 
outside of these; then by examining our cut of the sacrum in Catharista 
atrata (and the condition obtains next best in Gyparchus), we observe how 
it occurs among others; they are confined almost to the few ultimate 
vertebre in Pseudogryphus and Sarcorhamphus. The anterior margins 
of the ilia are finished off above by a smooth and raised border, which 
