146 MEMOIRS OF THE CARNEGIE MUSEUM 



water birds. The radial crest is reduced to a long, low, inconspicuous ridge, and, 

 in fact, this proximal end of the humerus, as a whole, merges into the shaft so 

 gradually from both sides, and its being so narrow withal, that we are rather im- 

 pressed with its lack of strength and an absence of a certain robustness so characteristic 

 of the bone in other birds of equal size and that lead a similar life. This in no way- 

 applies, hoAvever, to the shaft itself, for this subcylindrical and hollow, bony tube, with 

 its double sigmoidal curve, carries with it the very elements of strength and power. 



Its distal extremity lacks but little of being as wide as the widest part of the 

 head of the bone. It is without an ecto-condyloid process, has the trochleas very 

 prominent, and presents for examination a deep fossa to the anconal side of the 

 ulnar tubercle. 



The shaft of radius for so long a one is unusually straight, and only a slight 

 curve is noticed in the proximal moiety of the ulna. 



In its continuity the former bone is subtrihedral in its form, with its pneumatic 

 foramina situated beneath the transversely expanded portion of the distal end. 

 Muscular lines mark this radial shaft along its inferior aspect. 



For its distal moiety the shaft of ulna is nearly cylindrical in form, but this is 

 gradually exchanged for the subtrihedral as we pass over the proximal half of the bone. 



It presents for examination a double row of feebly marked papillse for the quill- 

 butts of the secondary feathers. 



A long, shallow, though notable fossa is seen at the proximal and anconal side 

 of the shaft, which terminates in a single pneumatic foramen just beyond the promi- 

 nent cup-shaped articulation for the ulnar tubercle of the humerus. 



Other pneumatic holes occur at the distal end of the ulna upon all sides, except 

 the outer one. The olecranon, though large and rather tuberous, would not particu- 

 larly attract our attention. A distinct canal up(m the outer aspect of the distal 

 end of the shaft for the passage of the tendons characterizes this bone. The artic- 

 ular surface shows nothing of special interest. 



As usual, the carpal segments are but two in number — a radiale and an ulnare. 

 They present the forms and facets common to these bones generally. Both are 

 pneumatic and have large apertures for the admission of air to their hollow interiors. 



The carpo-metacaijncs also presents a number of those foramina at either of its 

 extremities; the principal one, however, is found just below the trochlear surface 

 formed by os magnum upon the anconal side of the bone. A notable process occurs 

 immediately below it, as well as another group of these air-holes, in its outer as- 

 pect, near the short and inconspicuous first metacarpal. 



The main shaft is straight and of good caliber ; on the palmar side it is longitudi- 



