1900.] SHUFELDT—OSTEOLOGY OF THE STRIGES. TOL 
In the figures given in my memoir on Sfeofyfo and other indi- 
viduals like it, the clavicles were pneumatic. Again, in both 
young and old, it may have any of its lower parts completed by 
cartilage; it never displays a mesial expansion of bone at the 
point of confluence. As already shown, the superior entrance of 
the anterior;groove on the coracoid is a complete circuit, formed 
by the three bones of the group. The head of the coracoid over- 
hangs it above; next below is the clavicle, closing it in anteriorly ; 
lowest of all the scapula behind. A plane passing through the 
superior margins of this aperture would look upward, inward and 
backward. All the bones of the scapular arch are pneumatic, 
with the exception sometimes seen in the clavicle; and the 
foramina, to allow the air to enter their interiors, look into the 
enclosed groove of the coracoid just described. In the scapula 
the foramen is usually single and in the acromion process ; single 
again inthe clavicle, it is seen in the broadest part of the head, 
while in the coracoid there is generally a group of these little aper- 
tures, situated in the depression on the surface that overhangs this 
entrance to the coracoidal groove. 
As in many others of the family, in common, too, with not a few 
of the diurnal Raftores, this Owl possesses an os humero scapulare, 
of the usual form, that increases the articular surface of the 
shoulder-joint for the humerus. 
Of the Upper Extremity.—The upper extremity consists of ten 
distinct bones in the full-grown bird, omitting minute sesamoids 
that may possibly exist. These are the humerus of the arm, the 
radius,and ulna of the forearm, two free carpels, the metacarpal 
and four phalanges. The humerus is a long, extremely light and 
smooth bone, and when viewed from above in its position of rest, 
with the wing closed, it reminds one of the curve in the small 
italic letter /, being concave above toward the scapula. And this 
bone is so twisted that this same curve is exhibited, though not 
quite as well marked, when viewing it laterally. The humerus is 5.5 
centimetres long, subcylindrical on section at midshaft, at which 
point a minute aperture exists for the passage of the nutrient ves- 
sels that are distributed to the osseous tissue and its internal lining. 
This foramen enters the bone very obliquely, its external orifice be- 
ing nearest the proximal extremity. This end is well expanded, and 
surmounted above by a strongly developed radial crest that over- 
hangs the shaft slightly toward the palmar aspect. It occupies a 
° 
