SHUFELDT.] OSTEOLOGY OF THE SPEOTYTO. 615 
depressions for the origin and insertion of muscles. Approaching the 
wrist, the shaft is seen to be generally smooth, and diminishes in eali- 
bre at junction ot middle and proximal thirds, in the locality of the 
nutrient foramen, while along its entire length, at certain intervals, are 
the slight elevations 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 as large as the proximal end. The articulating- 
surface has a deep mesial cleft in the vertical direction, limited exter- 
nally by an elliptical curve, internally by a double, tuberous knob for 
articulation with the irregularly formed cuneiform of the carpus, while 
above is a roughened surface that is covered by the expanded end of the 
radius.} 
The carpus is composed of the scapho-lunar, 0s magnum, and cuneiform. 
The scapho-lunar articulates with radius, os magnum, and ulna. The 
radial articulation is a rather deep and elliptical concave facet, its lower 
border gliding over the ulna, while the distal end of the radius plays in 
the concavity. The opposite face of this six-sided little .bone is also 
smooth, and is a nearly flattened surface that articulates with os mag- 
num. The upper and lower surfaces, as well as the ends, are simply 
roughened and fashioned to give the proper form to that part of the joint 
into which it enters, and for the attachment of ligaments. Os mag- 
num has become confluent with the mid-metacarpal, forming its troch- 
lear surface for articulation with scapho-lunar, cuneiform,and ulna. The 
cuneiform is an extremely irregularly shaped bone; it appears to be 
rather the larger of the two free carpals, and is the lower in regard to 
position. *It articulates with ulna and os magnum, simply. Its outer 
ulnar facet is elliptical and shallow, monopolizing the entire face of the 
bone; its inner facet is very irregular, being formed so as to accommo- 
date itself to the ulnar tubercles, with which it articulates. Projecting 
towards the metacarpus, this little bone has two prongs or limbs, the 
inner aspect of the extremities of each possessing a subcircular facette 
that articulates, the outer and shorter limb with the internal trochlear 
margin of os magnum, on the same side; the inner and longer limb strad- 
dles the metacarpal and glides over the surface, during movements of the 
joint, at a point about where magnum becomes confluent with mid-meta- 
carpal. The cuneiform has also attached to it ligaments that enclose 
the wrist-joint beneath—capsular ligaments of the carpus. 
The metacarpus is formed in the usual manner, by the amalgamation of 
the index, medius, and annularis metacarpals, the first, second, and 
third, respectively. It is 3.3 centimetres long, articulating with scapho- 
lunar, ulna, and cuneiform at its proximal extremity by means of os mag- 
num, that has become anchylosed with mid-metacarpal and the pha- 
1In the October number of the Bulletin of the Nuttall Ornithological Club, for 1881, 
Cambridge, Mass., I published an article entitled ‘‘On the ossicle of the Antibrachium 
as found in sone of the North American Falconide”; wherein I described a very inter- 
esting sesamoid that was found above the carpal articulation, on the radius, in a speci- 
men of Circus hudsonius. This sesamoid I named the os prominens, but subsequently 
ascertained that it had been noticed by Milne-Edwards, and after this naturalist, by 
Mivart (Lessons in Elem. Anat., p. 320, Lond., 1877). My attention was afterwards 
called to its occurrence in the Owls, by Mr. Forbes, prosector to the Zodlogical So- 
ciety of London, and again by Mr. F. A. Lucas, of Rochester, New York, the latter 
observer finding it in Bubo and Nyctea. Subsequently I found it in other American 
Owls, and have no reason to doubt but that it will be found in Speotyto, though I have 
not material at hand, now, to confirm it. Additional literature and remarks upon 
this sesamoid will be found in following numbers of the Bulletin quoted above; one 
in the January number, 1882, by Mr. J. A. Jeffries. It does not show in the carpus of 
Bubo virginianus (Plate III, Fig. 11), accompanying this article, becanse af the time 
I drew the figure I was not aware of its occurrence in that Owl, or the joint repre- 
sented would have been placed so as to exhibit it. 
