46 R. W. SHUFELDT, 
from which locality it deepens again to the termination of the bone 
posteriorly. Anteriorly, the thickened border is convex outward, 
and rounded throughout. Down the median line, and all round 
within the costal borders, are little groups of pneumatiec fora- 
mina, for this bone is highly pneumatic. Sometimes, within the 
anterior border in the median line, there is a deep, oval, circum- 
seribed concavity, with the pneumatic foramina at its base (D. autum- 
nalis, 455). This varies in its form, or may be replaced by a large, 
single pneumatic foramen. 
Prof. R. H. Burxe, of the Royal College of Surgeons of Eng- 
land, to whom I am greatly indebted for having examined the sterna 
of Dendrocygna fulva, D. javanica, D. eytoni and D. arborea in the 
collection of that institution, has, with great kindness made and sent 
me sketches of this locality in the bone for those several species. 
His figures show that, in a specimen of D. (fulva) bicolor, this “pit” 
is deep, and divided by a median central “bar”, which latter is ab- 
sent in D. eytoni (No. 1430), while in D. javanica (No. 1432) the 
character exists as in D. fulva (bicolor), but the pit and bar are 
not so marked. The pit is very slightly marked in D. arborea 
(No. 1434). 
In Branta canadensis (No. 17980, U. S. Nation. Mus.), this “pit” 
or fossa may be distinely ceircumscribed, very deep, of an oblong 
shape (placed lengthwise); with shallow fossae on either side of it, 
all having pneumatic foramina at their bases. There is no fossa in 
a specimen of Aöx galericulata, and only a clean-cut, single, ceircular 
pneumatic foramen present. This is the case in a specimen of 
Harelda hyemalis; but in it the foramen is a mere pinhole (No. 18627, 
Coll. U. S. Nation. Mus.). 4Aiz sponsa (No. 18612, Coll. U. S. Nation. 
Mus.) agrees with Aöx galericulata (No. 18271, Coll. U. S. Nation. 
Mus.). In Mergus serrator it is a clean-cut, deep, circular pit, with 
a minute foramen at its base in the middle line; though I am in- 
clined to think that this sternum is non-pneumatic. Chenonetta jubata 
has a medium-sized, circular foramen there, but no pneumatic opening 
elsewhere in the bone. Polysticta stelleri has no fossa there at all, 
nor foramen, as the sternum of this eider is completely non-pneu- 
matic. In Olor columbianus there is a raised median bar sloping 
backward from the anterior border, with a few foramina upon either 
side ofit. Cereopsis has a circumscribed fossa with a group of small 
pneumatic foramina at its base; while in Hymenolaemus malaco- 
rhynchus there is a single pit of small size, and the sternum is non- 
