OSSEOUS SYSTEM OF AVES. 67 



and commonly also with the clavicle. It thns forms the main sup- 

 port to the wing, and point of resistance to the humeri during the 

 downward stroke of the aerial oar. The humeral end of the bone 

 is commonly bifurcate; the outer process is the strongest, and 

 forms the fore part of the glenoid cavity {I, fig. 19), above which 

 it rises, to a greater or less extent, and usually affords, on its 

 inner side, an articular surface for the clavicle : the inner process 

 is short and compressed, articulates with the scapula, and is also 

 joined by ligament to the end of the clavicle. The coracoid is 

 perforated at the base of the inner process. The coracoid is of 

 great breadth in the Albatross, fig. 13, h, h ; and is both long 

 and strong in the Penguin, fig. 19, 52. It is pneumatic in Aves 

 aerecB and in Rasores ; in some GrallcB (Psophia), and in most 

 longipennate Palmipeds. The sternal ends of the coracoids join 

 each other in Tachypetes, decussate in Herons, send up a process 

 above the mesial end in Aptenodytes and above the lateral or 

 outer end in Tachypetes : the outer angle of the sternal end is 

 produced in Raptores. The glenoid cavity resulting from the 

 union of the coracoid and scapula is not equal to the reception 

 of the entire head of the humerus. In Raptores, Scansores, and 

 Cantores, an ossicle (O5 humero-scapulare) lies between the 

 scapula and humerus at the upper and back part of the glenoid 

 cavity. In Rasores, Grallatores, and Natatores, there is, in 

 place of this bone, a strong elastic ligament or fibro-cartilage 

 extended between the scapula and coracoid, against which that 

 part of the head of the humerus rests, which is not in contact 

 with the glenoid cavity. 



The clavicles, figs. 15, 16, 18, 19, 58, are the most variable 

 elements of the scapular apparatus. In the Ground Parrots of 

 Australia (Pezopliorus, Illiger) they are rudimentary or wholly 

 deficient ; they are slender styles in Columha galeata ; they are re- 

 presented by short processes in the Emeu, Phea, and Cassowary ; 

 they do not come in contact inferiorly in the Ostrich, although 

 they reach the sternum. In the Toucans they are separate, and 

 do not reach the sternum. In the Hornbills and Screech Owl 

 {Strix Ulula) they are united at their inferior extremities by car- 

 tilage. In the rest of the class they are anchylosed together 

 inferiorly, and so constitute one bone, the furculum or * merry- 

 thought.' From the point of confluence a compressed process ex- 

 tends downward in the Diurnal Raptores, the Conirostral Cantores, 

 the Rasores, most of the Grallatores, and Natatores, in which a 

 ligament extends from its extremity to the ento-sternum. The 

 process itself reaches the sternum, and is anchylosed therewith 



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