324 NEW YORK STATE MUSEUM 



fourchette of some of the ducks. In it the free clavicular heads 

 are flattened on top, and, as usual, drawn out into pointed apexes 

 posteriorly. The bone is completely nonpneumatic, and its supra- 

 clavicular processes pretty well developed. It is of the broad U- 

 arch variety, being found, for the most part, in a plane at right 

 angles to the heads of the clavicles. These last are laterally com- 

 pressed, as is the whole bone, but this compression gradually comes 

 to be anteroposterior as it approaches the inferomesial point, where 

 it is entirely so. At the back of this region, a low, diffused tubercle 

 may be seen, the barest indication of an hypocleidium. In B r a n t a 

 canadensis, both the coracoid and the scapula are pneumatic 

 elements of the shoulder girdle. The former is a very stout bone, 

 with tuberous head; strongly developed scapular and glenoidal 

 processes ; a shortish shaft, that is somewhat compressed in the 

 anteroposterior direction, and marked with obliquotransverse mus- 

 cular lines upon its hinder aspect. Below, the sternal extremity 

 is much expanded, and develops a big facet for the sternum. The 

 epicoracoidal process is not especially distinct, and the pneumatic 

 foramina for the bone exist principally upon its superomesial side, 

 directly beneath the overhanging rim of the tuberosity of the sum- 

 mit. A great valley exists here, curving downward and inward to 

 run out upon the extensive transverse scapular process below. 



A scapula presents the usual ornithic characters of the bone, hav- 

 ing an expanded head ; thick for its anterior moiety, but the distal 

 half of the body gradually becoming considerably thinner; the entire 

 bone being more or less compressed in the vertical direction. As 

 a whole it is curved both in the transverse and vertical planes, the 

 concavities being upon the nether and externolateral aspects. Its 

 posterior free end is abruptly truncated, in a slightly oblique di- 

 rection, so little so, indeed, that it gives it the appearance of being 

 nearly square across. When articulated, in situ, with the coracoid, 

 its chord makes an angle with the longitudinal axis of that bone of 

 about 60°, 



Apart from the bones being one third smaller in size, the coracoids 

 and scapulae ofAnser albifrons exhibit characters that are 

 practically identical with the corresponding ones as found in 

 Branta canadensis. These two elements of the arch are 

 also pneumatic in Anser, and, as in all geese and ducks, at the 

 outer end of the transverse facet upon the coracoid for the scapula, 

 there is a well marked, circular concavity, intended to accommodate 

 a hemispherical facet just within the glenoidal process on the head 



