“Tree-Ducks” of the genus Dendrocygna. 31. 
plorers, — any one of whom could easily have secured all the 
skeletons of Philacte that could be desired. 
Before giving a detailed description of any of the parts, or 
the bones of the trunk skeleton, of Dendrocygna and other anserines 
I propose to present here a Table, giving comparative data of 
the vertebrae, ribs, etc. in a number of the Anseres, in that we 
may see how they compare in these respects, and especially with 
regard to the Tree-Ducks in such matters. 
With respect to the number of vertebrae in the spine of Dendro- 
cygna, in so far as the two North American species are concerned, 
it will be observed from the following Table that these birds most 
nearly agree with such a species as Netta rufina; while on the 
other hand, what is far more important, it is quite clear that from 
a numerical standpoint, as applied to the vertebrae, these two 
dendrocygnine species, at least, belong with the Anatinae, and 
not with the Anserinae, or much less with the Cygninae. 
To institute comparisons of the vertebrae, then, in the case 
of any two species of ducks, swans or geese, it is very obvious that 
the two forms thus compared should have exactly the same 
number of vertebrae in their spines, or else such a description 
would become. practically useless after passing the atlas and axis. 
For example, it would be useless to make a comparative description 
of the cervicodorsal vertebrae of a Dendrocygna with that 
of an Aix, the first having 22 vertebrae in that division of the 
spine, and the latter only 21. The 19th vertebra, for example, in 
the spine of Dendrocygna autumnalis, might be the 19th in Aix 
sponsa, or it might not; the chances are that it is not, and for the 
reason just given above. Even still more useless and unscientific 
would it be to compare, vertebra for vertebra, in the spine of any 
representative of the genus Dendrocygna with those in the spine of 
a swan, such as Olor buceinator, and for exactly the same reason. 
There is considerable data on the axial skeleton of the 
Anseres in my above cited work on the “Osteology of Birds”, and 
some of this refers to a specimen of Dendrocygna autumnalis (Coll. 
U. S. Nation. Mus. No. 1491). This will be included with what is 
set forth here, in the light of far more complete and extensive 
material. 
In a skeleton of Dendrocygna autumnalis (454), collected in Texas 
by Mr. F. B. Armstrone, the atlas presents the same characters 
that it does among the Anatinae generally, and in some respects 
