Shufeldt on the Os Prominens in Hawks. 
201 
its existence in any of the American Owls. The opportunity of 
examining the skeleton of Sarnia funerea has never been 
afforded me. 
In the skeleton of Buteo borealis , from the collection of the 
Smithsonian Institution, we find this bone present, although of 
relatively smaller size as compared with Circus ; it also seems 
to articulate almost, if not quite, exclusively with scapho-lunar , 
barely coming in contact with radius at all. 
In the same collection we observe, in the skeleton of Halice- 
etus leucocephalus , the os prominens again present, and here 
of a more quadrate outline and figure, though evidently designed 
to carry out a like purpose as in the other diurnal Raptores. 
The skeletons of Accipiter cooperi that I have examined, an 
indifferent one in my own possession, and another, not entirely 
reliable, in the collection of the 'Army Medical Museum, Wash- 
ington, seem to be without these bones, and I am of the opinion 
that if this Hawk possesses them at all, they will be found to be 
very small as compared with others of the family. They are present 
in Archibuteo lagopns san cti-joha n nis y wh ere they again resem- 
ble these bones as found in Circus , differing principally in the 
position they occupy, being placed apparently still further towards 
the inner aspect of the joint. We find them also in Astur atrica- 
pillus , in Accipitcr fuscus, where they are quite prominent and 
elongated, and again in Pandicn , but further than this I have 
not looked into the' subject and would prefer, in any event, 
describing their exact size, position, and relation to surrounding 
parts from the recently killed specimens rather than from museum 
skeletons, as valuable as these subjects are to osteological students 
in so many other respects. 
We may be' certain that the os prominens will never be re- 
garded by any one in the light of one of the bones of the carpus, 
but articulating as it does with one of those bones and the distal 
end of radius, it will be the proper place in descriptive works 
or special monographs upon ornithotomical subjects to notice and 
describe it ; just as Professor Owen treats the os hwnero-scapulare 
of birds, directing attention to it under the section treating of 
the Scapular Arch and Appendage, where he says: “ In Rap- 
tores^ Scansores , and Cantor e$ , an ossicle (os humero-scapulare) 
lies between the scapula and humerus at the upper and back part 
of the glenoid cavity.” (Comp. Anat. & v Phys. of Vert., Vol. 
