662 



BIRDS. 



hyoid consists of a flat "body," with anterior and posterioi 

 " horns," the latter derived from the first branchial arch. 



The pectoral girdle consists of sabre-like scapulae extend- 

 ing dorsally over the ribs, of stout coracoids sloping ventrally 



and articulating with the sternum, of the clavicles which are 

 united by the interclavicle to form the merrythought or 

 furcula. The opening left where the upper ends of the 

 clavicles touch the scapula and coracoid is called the fora- 

 men triosseum* 



