702 SHUFELDT—OSTEOLOGY OF THE STRIGES. [Dee. 7, 
line on the bone from the articular facet for the shoulder-joint to a 
point one-third down the shaft. The ulnar crest, or lesser tuber- 
osity, encloses quite an extensive fossa below, which acts also as a 
partial screen to the pneumatic foramina, for the humerus is highly 
pneumatic. These foramina usually consist of one circular open- 
ing, surrounded by a group of many smaller ones. In young. 
birds a very large foramen is generally present; this closes in as 
age advances. Between the two tuberosities is the vertical and 
elliptical convex facet for articulation with the glenoid cavity of 
the shoulder-joint, constituting the ‘‘ head of the humerus.’’ The 
radial crest displays palmad, a ridge for the insertion of the tendon 
of the pectoralis major. The distal end of the humerus is also ex- 
panded in the vertical plane and gently convex anconad—the re- 
verse condition of the proximal extremity. It presents for exam- 
ination the articular facets for the ginglymoid joint it forms with 
radius and ulna and the superior and inferior condyles. The 
larger, and at the same time the superior, of these two facets is 
intended for the cup-shaped depression in the head of the radius, 
as well as a portion of the articular surface on the ulna. It is 
ovoid in form, and placed obliquely on the bone, the inferior end 
of the long axis of the oval being situated the nearer the proximal 
extremity of the shaft. This facet is separated from the trochlea 
surface for the ulna by a well-marked depression; this latter is a 
knoblike tubercle when compared with the radial facet. ‘The con- 
dyles and the entire articular surface are about in the same plane 
posteriorly—that is, neither increases the length of the bone one 
more than another. Passing from the trochlea surface for the ulna 
toward the inner aspect of the shaft, there is to be observed a 
shallow depression, which corresponds to the olecranon fossa of 
human osteology, and in full extension of the limb allows room for 
that process of the ulnain this bird. The radius has an average 
length of 6.6 centimetres, and the ulna a corresponding length of 
6.8 centimetres, so that their distal extremities when articulated, 
as we examine them in the closed wing, extend beyond the head 
of the humerus. In this position also the radius occupies a higher 
level than the ulna, and is the innermost bone of the two. The 
radius is slender, the transverse diameters of its subcylindrical 
shaft varying but little throughout its extent, though its extremities 
are expanded. From the elbow-joint, when the two bones are in 
position, it at first diverges from the ulna at a moderate curve, to 
