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OSTEOLOGY OF BIRDS 



side, where either of these latter merge with the limbs, we find a 

 peculiar little peglike process, that is quite characteristic of most 

 Anatinae. The scapular is long and curved, the curve being in 

 the plane of its blade, with the convex border mesiad. Its posterior 

 end is simply rounded off, and its head makes a firm articulation 

 with the broad, scapular process of the coracoid. This latter bone 

 has its shaft much compressed from before, backward, while its 

 sternal extremity develops an unusual expansion, the inferoexternal 

 angle of which is truncated. 



Querquedula discors and other teals, as well as the 

 Mallard, agree in their pectoral arches, in the main, with the one 

 just described for Spatula. It has, however, a rudimentary hypo- 

 cleidium present. 



This latter feature is entirely absent in Clangula, where the 

 furcula is very strong and its arch very broad. Otherwise the bone 

 is generally marked by all the characters it bears in the ducks. 

 The blade of the scapula in Clangula is much arched, and shorter 

 and broader than it is in the teals. The coracoid presents nothing 

 peculiar, having much the same form that it has in Spatula, though 

 it agrees with the teals in having a comparatively longer shaft. 



In Dafila acuta I find a furcula of the same form as in 

 Spatula, the rounded bone being of uniform caliber throughout, and 

 the coracoid of this duck possesses precisely similar characters, but 

 its thin bladelike scapula is very long and very much curved, and 

 terminates in a sharp point behind. 



In the genera Marila, Aix, and Netta the same osteological char- 

 acters of the shoulder girdle prevail, no departures being noticed 

 beyond the most trifling kind. 



H a r e 1 d a hyemalis has the free ends of the clavicles well 

 drawn out, and the limbs of the arch are not so spreading. The scap- 

 ula is less curved throughout its length, the blade being uniform in 

 width, and the bone terminates behind in a squarely truncated end, 

 with the angles just barely rounded off. A coracoid of this duck 

 is relatively shorter than usual, with its sternal extremity very much 

 expanded. Polysticta stelleri possesses a shoulder girdle 

 very similar to this, while in Somateria mollissima the 

 furcula is again seen to be very spreading; the blade of the scapula 

 less curved, having its distal extremity acutely truncated. A cora- 

 coid of this eider is compressed in the anteroposterior direction, 

 with a much expanded sternal end. All these characters are em- 

 phasized in Somateria v . nigra, where the free extrem- 



