1900.] SHUFELDT—OSTEOLOGY OF THE STRIGES. 703 
approach that bone again to nearly absolute contact at the junction 
of middle and distal thirds by a more gentle curve; from this 
latter point it lies parallel with the uina to the wrist. The head of 
the radius is elliptical, being crowned by a depression for articula- 
tion with the oblique facet on the distal end of the humerus. 
Beyond, below, and to the outer aspect of this facet is another of 
similar form, though convex, for articulation with the ulna, while 
still more advanced toward the distal end we find the bicipital 
tuberosity, and, beyond, the minute nutrient foramen, all of the 
bones beyond the humerus being non-pneumatic. © The distal 
extremity of the bone in question is terminated by a fanlike 
expansion that caps the ulna and articulates by its anterior convex 
margin with the radiale of the wrist. It is marked above by the 
longitudinal groove for the tendon of the extensor metacarpi 
radialis longus. The shaft of the ulna is nearly three times as 
large as that of the radius. Its outer half is straight, its inner 
curved toward the humerus, thereby increasing at the proximal 
moiety the interosseous space by the assistance of the opposite 
curve made by the radius. ‘The stronger end is the one involved 
in the formation of the elbow-joint ; here is to be observed the 
depression for the head of the radius, or the lesser sigmoid cavity, 
while the articular surface beyond that occupies the entire end of 
the bone, directed downward, inward and backward, presents for 
examination the greater sigmoid cavity, the olecranon and coronoid 
process, and the cavity for articulation with the oblique facet of 
the humerus. The greater sigmoid cavity is subcircular and of 
some depth; its lower and produced lip represents the coronoid 
process, as does its upper, better-marked and more tuberous pro- 
longation represent the olecranon of andranatomia. Extending 
radiad is another concave, quadrate, articular facet for the oblique 
tubercle of the humerus, as the first-mentioned concavity articulates 
with the ulnar tubercle or trochlea. A little beyond this articular 
surface are various small tuberosities and depressions for the origin 
and insertion of muscles. Approaching the wrist the shaft is seen 
to be generally smooth, and diminishes in calibre at junction of 
middle and proximal thirds in the locality of the nutrient foramen, 
while along its entire length at certain intervals are the slight ele- 
vations for the apices of the quills of the secondaries. The distal 
extremity of the ulna enters into the formation of the wrist joint ; 
it is not nearly so large as the proximal end. ‘The articulating sur- 
