2t6 



GENERAL ORNITHOLOGY 



clavicles keep the shoulders apart from each other. The scapular 

 arch is always present and complete ; the clavicular is sometimes 

 defective or wanting. There are two leading styles of scapular 

 arch, corresponding to the ratite and carinate sternum. (1) In 

 RatitcB the axes of the coracoid and scapula are nearly coincident 

 (for the most part in a continuous right line) and ankylosed to- 

 gether ; the clavicles are usually wanting, or defective ; and the 



coracoids are instepped on 

 the sternum far apart. (2) 

 In all Carinaice the axes 

 of the coracoid and scapula 

 form an acute or scarcely 

 obtuse angle (Figs. 56 and 

 59, sglc) ; normally these 

 bones are not ankylosed; 

 perfect clavicles are present, 

 ankylosed with each other, 

 but free from the other 

 bones ; and the coracoids 

 are instepped close together. 

 Decided exceptions to these 

 conditions, as in Notornis, 

 are anomalous ; though in- 

 completion of the clavicles 

 repeatedly occurs, as noted 

 below. 



The Coracoid (Gr. Kopa^, 

 Jcorax, a crow; elSos, eidos, 

 form : the corresponding 

 bone of the human sub- 

 ject, which is the stunted 

 "coracoid process of the 

 scapula," being likened to 

 a crow's beak ; no applica- 

 bility in the present case ; 

 Figs. 56 c, 59 c) is a 

 stout, straight, cylindric 

 bone, expanded at each end, extending forward, outward, and 

 upward from the fore border of the sternum to the shoulder. 

 Its foot is flattened and splayed to fit in the articular groove 

 of fore border of the sternum already described; it often 

 overlaps that of its fellow on the median line; is narrower and 

 remote from its fellow in Batitce. The head of the bone, irregu- 

 larly expanded, articulates or ankyloses with the end of the scapula, 

 and also usually with the clavicle. It bears externally a smooth 



Fio. 69.— Hightpeotoral arch of a bird, Pedimcetespha. 

 sianellus, nat. size, outside view ; Dr. R. W. Shufeldt, 

 U.S.A. s, scapula; c, coracoid ; ffZ, glenoid, the cavity 

 for head of humerus ; cl, clavicle ; he, hypoclidium. In 

 situ, the right end of the figure should tilt up a little ; 

 see Fig. 66. ■ 



