692 SHUFELDT—OSTEOLOGY OF THE STRIGES. [Dee. 7, 
when compared with the remainder of its skeleton with regard to 
areas for muscular attachments, reveals to us the disproportion of 
the surface supplied by that bone for the attachment of the pecto- 
rals. That its dimensions are relatively contracted is proved by 
actual comparative and proportional measurements of the bones 
with other species of its family, individuals of which, at the best, 
are not noted for their powers of flight, as a rule, and of a conse- 
quence the sternum does not present so prominent a feature of the 
skeleton as it does in other species of the class Aves where vigorous 
flight is habitual. The concave dorsal aspect of the body is smooth, 
being traversed in the median line by a very shallow groove that les 
immediately over the base of the keel. This groove terminates, 
within five millimetres of the anterior border, in a litttle depression, 
at the bottom of which are discovered pneumatic foramina, two or 
more in number, leading to the anterior vertical ridge of the carina 
beneath. Other minute openings for the admission of air into 
the interior of this bone are seen among some shallow depres- 
sions just within the costal borders. The bone does not seem to 
be as well supplied in this respect as it is in some other Owls. The 
costal borders supporting the transverse articular facets for articula- 
tion with the sternal ribs occupy anteriorly about one-third of the 
entire lateral border on either aide. At the bases of the majority of 
the depressions that occur between these facets are found other 
pneumatic foramina. The anterior border is smooth and rounded, 
with a median shallow concavity occupying its middle third. At 
its extremities, laterally, the costal processes arise with a general 
foward tendency at first, but with their superior moieties directed 
backward. ‘The costal borders terminate at the posterior borders 
of these processes at a higher level than the anterior margin does 
at their anterior borders. The coracoid grooves are just below 
the anterior border. They are deep, continuous with each 
other, having a greater depth behind the manubrium in the 
median line than observed at any other point. Their gen- 
eral surface is smooth and polished, looking upward and forward, 
and lying principally in the horizontal plane. They melt away 
into the body of the bone laterally at points opposite and not far 
distant from the posterior articulations on the costal borders. The 
margin that bounds them below is sharp, travels at right angles 
from the median line, at first to a point posterior to the costal pro- 
cesses, then making a little dip downward, then again curving up- 
