164 



TEE BONliti. 



coalescing with that of the opposite side, a single bone called the fork {furndum), 

 or osfwculare. The scaptda (Figs. 10!), k ; 111, a S) is narrow, elongated, and 

 falciform, and shows no trace of a spine. Its anterior extremity only forms a 

 portion of the glenoid cavity, and is united by means of a fibro-cartilage with 

 the fork of the coracoid bone. The latter (Figs. 109, l ; 111 a 9) is so named 

 because it represents the coracoid process of Mammals, and is a long prismatic 

 bone, directed obliquely from above downwards, and before to behind. Its 

 superior extremity is often fused with the scapula, and united at an acute angle 

 with that bone to form a portion of the articular cavity which receives the head 

 of the humerus. Its inferior extremity is flattened from before to behind, and 

 responds by a diarthrodial articulation to the anterior border of the sternum. 

 The coracoid is long in Birds which fly slowly ; it is, on the contrary, short, 

 thick, and therefore very solid, in quick flyers. T\iq fork (Figs. 109, m; 111, 



Fig. 111. 



STERNTTM AND BONES OF THE WING. 



A, Sternum and wing-hones of the Fowl (upper face). 1, Body of the sternum ; 2, its episternal 

 process; 3, 3, its costal processes; 4,4, its lateral external processes; 5, 5, its lateral internal 

 processes; 6, 6, internal notches; 7, 7, external notches; 8, scapula; 9, coracoid; 10, fork; 

 11, opening for the passage of the elevator of the wing; 13, humerus; 14, air-opening in that 

 bone; 15, ulna; 16, radius; 17, ulna-carpal bone; 18, radio-carpal bone; 19, large metacarpal; 

 20, small metacarpal ; 21, first phalanx of the large digit ; 21', second phalanx of ditto ; 22, small 

 phalanx lying beside the first bone of the large digit, and representing the remains of a third digit ; 

 23, thumb. 



B, Sternum and shoulder-bone of a young Duck (inferior surface). 1, 1, Sternum; 2, keel; 3, 3, 

 lateral notches ; 4, 4, coracoid ; 5, 5, fork ; 6, opening for the passage of the elevator of the wing. 



B 5, 5) is a single bone, shaped like a V or U, situated at the base of the two 

 wings, in front of the trunk, and in an oblique direction downwards and back- 

 wards. The two branches which form it represent the clavicles : they meet and 

 are united at their inferior extremities, where they describe a curvilinear angle 

 more or less open, attached to the brisket by means of a membranous ligament 



