“Tree-Ducks” of the genus Dendrocygna. 21 
No. 17118, Coll. U. S. Nation. Mus.), we note that the basitemporal 
in each is a convex, rounded are, carried to a sharp, minute spine 
anteriorly, above which the Eustachian entrances are exposed. In 
each, the temporal plates of the exoceipitals (paroceipitals) are large 
and triangular in form, being perpendicular to the cranial base. 
The condyle is mesially notched above, and a concavity is found 
in the basioceipital anterior to it. 
A quadrate in either of these ducks is large for the size of 
the bird, as compared with the quadrate in many other species 
possessing a skull of equal size. 
There are two facets placed in line transversely, on its man- 
dibular part, they being separated by a valley from the hinder part 
of the bone, which latter is rounded. Above this, on the postero- 
auricular margin of the quadrate, there is usually developed in 
Dendrocygna a small up-turned apophysis. This process is barely to 
be perceived in the Mallard, while it is found in other anserines, 
not especially related, as in Somateria v-nigra, and in some of the 
species of Oidemia, as 0. perspieillata. 
The articular head of the mastoid process of the quadrate in 
both Anas and Dendrocygna presents adouble facet, with a sharp 
grove standing between them; while the orbital process in both 
these genera is triangular, pointed an individualized. Below it is 
the small hemiellipsoidal facet for the pterygoid of the same side. 
A pterygoid in any of the Anseres is a very distinctive 
bone, and to this neither Anas nor Dendrocygna form any exception. 
Its anterior extremity is more or less massive, and presents, at its 
apex, a hemispherical cup for articulation with the hemispherical 
facet on the palatine of the same side. A process is developed both 
above and below this cup, while on the upper border of this end of 
the pterygoid is a large, elliptical, longitudinal facet for articulation 
with the similar one on the presphenoidal rostrum. When the skull 
is held: horizontally, this latter is directed upwards and forwards, 
to coossify, anteriorly, with the massive mesethmoid, which underlies 
the frontals posterior to the cranio-facial hinge. 
A palatine in either of the ducks now being considered and 
compared, is expanded anteriorly, compressed from above, downwards, 
being wedged in between the maxillary and maxillo-palatine of the 
same side, with which bones it very extensively coossifies. Mesially, 
the bone curls upwards, inwards, and then outwards, to terminate 
in a sharpened margin, which latter is lost on the aforesaid flattened 
