Shufeldt on the Os Prominens in Hawks. 201 



its existence in any of the American Owls. The opportunity of 

 examining the skeleton of Surnia 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 s:tme collection we observe, in the skeleton of Haliiv- 

 ctus 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 lagop7is sancti-johannis, where 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 Accipiter fuscus. where they are quite prominent and 

 elongated, and again in Panditn, 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 hu?nero-scapularc 

 of birds, directing attention to it under the section treating of 

 the Scapular Arch and Appendage, where he says: kk In Rap- 

 tores. Scansores, and Cantor es, an ossicle (os humero-scapularc) 

 lies between the scapula and humerus at the upper and back part 

 of the glenoid cavity." (Comp. Anat. & Phys. of Vert., Vol. 



