50 R. W. SHUFELDT, 
the U. S. Nation. Museum (sex not known) has a humerus that has 
a length of 9,7 cms, and is likewise pneumatic; but the fossa is very 
shallow, and only one or two very minute foramina are to be found 
at its base. 
The shaft of the bone is smooth and exhibits the usual sigmoidal 
curves. It is somewhat compressed from side to side, so that it. 
is ellipsoidal on sections at the shaft’s middle. On its upper side, 
proximally, the radial or superior crest, though well developed, is 
short, and extends down the shaft hardly more than does the crista. 
inferior or ulnar crest (Fig. 47 and 52 Pl. 8). 
Other features of this extremity of the bone are notably salient. 
in character, as the caput humeri and the tuberculum internum, 
with a deep, oblique incisura capitis between them. At the distal 
end the radial and ulnar trochleae are very pronounced; while the 
ectepicondylar and entepicondylar processes are much reduced, as 
they seem to be in most all Anseres. 
In Aix sponsa and Avx galericulata the humerus is likewise highly 
pneumatic, — the bone in these species being short and stout and 
but moderately curved. The caput humeri is made very prominent. 
by the unusual depth of the ineisura capitis and conspicuous tuber- 
culum internum. 
The depth of the pneumatic fossa in the humerus of Chenonetta: 
jubata is remarkable, and I have never seen its equal in the humerus 
of any bird of its size betore. The bone is pneumatic, and a nutrient. 
foramen is to be found at the middle of the shaft. From all ap- 
pearances, the humerus in Polysticta stelleri seems to be non-pneu- 
matic, and its radial or superior crest is short but prominent. The: 
distal trochleae are very protuberant and elegantly rounded of. 
(No. 15272, U. S. Nation. Mus., Ost. Coll). Having similar characters, 
pneumatic withal; smaller radial and ulnar tubercles, and a. 
slenderer shaft, — the humerus of Harelda hyemalis has a length 
of 7,5 cms. 
In Chen hyperboreus nivalis the bone is highly pneumatic, with 
a large, subeircular entrance in the pneumatic fossa. The projections. 
at the ends of the shaft forming its usual characters are not so: 
prominently developed as in the humeri of most Anatinae, the 
radial crest being low and produced somewhat further down the 
shaft. This latter exhibits the usual sigmoid curves, and is large 
in caliber, being almost cylindrical at its middle third. 
Cereopsis, with a very prominent pneumatic humerus, has its. 
