OSTEOLOGY OF BIRDS 



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of the scapula. This is a useful character in identifying these bones 

 in fossil anserine birds, generally. 



The character is very prominent in the coracoids of Chen 

 hyper borea nivalis, and these bones, as well as the scap- 

 ulae, are highly pneumatic in this goose. They agree with Anser 

 albif.rons in nearly all particulars, even in the matter of size. 

 Chen, however, has a slightly longer and rather more pointed 

 scapula, and below the scapular process of the coracoid, there is, in 

 Chen, sometimes an indication of a coracoidal notch. Both coracoids 

 and scapulae in Dendrocygna autumnalis are nonpneu- 

 matic, and the bones agree better with the ducks than they do with 

 the geese. Either scapulae in Dendrocygna is acutely truncated, 

 (from within, outward) at its distal end, the apex terminating 

 in a peculiar little rounded nib. The blade of the bone is very 

 nearly of uniform width, and presents the same curves that it does 

 in the geese. 



The humerus of the specimen of Branta canadensis that 

 I killed in Wyoming, (and already referred to above) has a length 

 of 19.5 centimeters, but the bone in a disarticulated skeleton of 

 this species, belonging to the United States National Museum, is 

 considerably less, as the entire bone is proportionately so. In 

 Anser albifrons the humerus has a length of about 15.2 

 centimeters, and in Chen hyper borea nivalis about 15.9 

 centimeters. In Dendrocygna autumnalis it measures 

 but 9.7 centimeters. Branta, Anser and Chen have characters 

 practically agreeing in the skeletons of their pectoral limbs, any 

 variation seen being very slight indeed; the bone differs, however, 

 in no small degree from the humerus figured by Beddard in the 

 Dictionary of Birds [pt 2, p. 439], and I am led to believe that that 

 figure must have been made from the humerus of a domestic goose. 



In Branta the bone is light ; highly pneumatic, and its subcyl- 

 indrical shaft exhibits the usual sigmoidal curves, while the nutrient 

 foramen at its middle is plainly seen. Both proximal and distal 

 ends present the usual ornithic characters found in this skeletal 

 segment of the wing. The head of the bone is largely developed, 

 and of a subellipsoidal convex form ; the incisura capitis being es- 

 pecially well marked 1 ; as is also the sulcus anconcii transversus. 

 The ulnar tuberosity is powerfully developed, and it handsomely 

 arches over a deep and capacious pneumatic fossa, at the upper 

 and inner side of which is to be seen the large, single, subelliptical 



1 This character is not shown in Beddard's figure at all. 



