BIRDS. 331 



and its place supplied by a ligament 1 . The two other clavicles 

 (clavicular coracoidece) are never absent; they lie more behind and 

 on the outside, are flatter, broader and shorter, and are attached to 

 the lateral margin of the uppermost part of the sternum. In 

 conjunction with the long thin scapula these clavicles form the 

 articular surface for the reception of the head of the humenis. In 

 many birds there is, in addition, a small bone present, which rests 

 upon the capsular membrane of the upper-arm bone at the side of 

 the scapula 2 . 



The upper-arm bone (humerus) is cylindrical; when the bird 

 does not expand its wings for flight this bone is directed back- 

 wards. It is especially long in the pelican, where it extends as 

 far as behind the pelvis, short in gallinaceous birds, where it 

 scarcely reaches to the last rib. In the ostrich it is long, in the 

 casuary, on the contrary, very short; also in the penguins (Apteno- 

 dytes) it is short and very flat besides. To the upper-arm bone 

 succeed the two bones of the fore-arm, of which the undermost and 

 thickest is the ulna (ulna s. cubitus), the uppermost the radius; 

 these bones also are particularly long in the pelicans, and especially 

 in the frigate-bird (Pelecanus aquilus L.). At the upper extremity 

 of the ulna is usually seen a small cubital process (olecranum), and 

 behind it there is often a pisiform bone or arm-pan (patella bra- 

 chialis) 5 . The wrist (carpus) is formed by two short little bones. 

 At its anterior margin the stiliform thumb is attached, which 

 consists of one or two joints (phalanges). Next to this lie two 

 tubular metacarpal bones, which have coalesced both above and 

 below. At the lower end of these bones are two fingers, of which 

 the outermost is small and consists of only one awl-shaped joint, 

 whilst the innermost, which extends far beyond the two other 

 fingers, is composed of two, or more rarely of three joints, of 

 which the first is broad and flat. 



1 Especially in the smaller species, as Psittacus pullarius ; compare KUHLMANN De 

 Absentia furculce in Psittaco pullario. Diss. inaug. Kiliae, 1842, 8vo. 



8 NITZSCH Osteografache Beitrage zur Naturgesch. der Vogel, Leipzig, 1811, a. 83 

 and foil. ; the author, who first noticed this bone, names it Scapula accessoria or 09 

 humero-capsulare. 



3 In Aptenodytes there are two such ossicles; see J. F. BKANDT Beitrage zur 

 Kennlniss der Naturgesch. derVogel mil besonderer Beziehung auf Skeletbau. St. Peters- 

 burg, 1839, 4to, Tab. xii. figs. 5, 6. 



