OSTEOLOGY OF BIRDS 



75 



in his Lessons in Elementary Anatomy [p. 320] also gives a cut, 

 (after A. Milne Edwards), showing its position in the wing of an 

 eagle ( A q U i 1 a fucosa). 



Later (April 1882), in the Nut tall Ornithological Bulletin, Mr 

 Frederic A. Lucas in his Notes on the Os prominens, made some 

 valuable additions to our knowledge of the subject, presenting a list 

 of many hawks and owls in which it occurred, and gave excellent 

 figures showing its position in Bubo v i r g i n i a n u s , O togyps 

 c a 1 v u s , and others. In the chapter on the Anatomy of Birds in 

 the second edition of his Key, I note that Professor Coues adopts 

 the name I originally bestowed upon this sesamoid. It seems that 

 a bone which attains the size it sometimes does in certain birds, 

 ought to be entitled to a distinctive appellation. 



The metacarpus of this harrier is a little over 6 centimeters 

 long. Its articular surface for the carpal segments is quite oblique, 

 and the part which originally was the first metacarpal, now forms 

 an unusually prominent and projecting process, slightly bent to the 

 anconal side. Wedged in between the proximal end of the bone and 

 the distal ends of ulna and radius are found the usual carpal ossicles, 

 the ulnar e and radiale. They differ in no marked respect from the 

 bones as found in nearly related forms. 



The poll ex has but one phalanx awarded it, but this bone is broad 

 and strong, presenting a considerable articular surface for the 

 metacarpus. This phalanx may support a claw at its extremity. 

 Second digit has two phalanges, the usual one with posterior border, 

 and the lower, long pointed one. In the former the expansion 

 arluded to is surrounded by a prominent^raised margin, but the area 

 it incloses is not perforated as in some birds. The little bone of 

 the third digit has a process developed upon its posterior edge, which 

 I have noticed in other birds, as for instance in Geococcyx. 



Pelvic limb. As in the upper extremity so we find it to be the 

 case here in this member; it is only the femur of the several bones 

 of the limb, that is pneumatic. A neat, elliptical orifice is found 

 on the anterior surface of the bone about the middle of its upper 

 third between the trochanterian ridge and the anterior muscular 

 line. This is its usual site when present in birds, and here admits 

 air throughout all parts of a comparatively large, but very light 

 bone. 



The head of this femur is rather small, and placed at a slight 

 angle on the shaft. Above, it is well excavated for the ligamentum 

 teres, between which concavity and the trochanterian ridge, here but 



