Osteology of Palaeornis. 
579 
the mesial aspect of the nasal and the maxillo-palatine of the same side. 
This is a large, fused, osseous mass in the skull of a macaw, while in 
Palaeornis these ossifications appear to be quite free and scroll-like. They 
appear to take the place of turhinals, and apparently have a similar function 
of increasing the osseous surface for the nasal mucous membrane. 
The sharp apex of the superior mandible, as in all parrots I believe, 
points directly downward, and is trihedral in form. In the macaws {Ara) 
the external narial apertures are extremely small for the size of the skull, 
they not having the diameter of those openings as seen in the skull of a 
specimen of Amazona leucocepliala in my collection, the skull of which latter 
is not one-third the size of that of the former species. Then, too, in the 
macaws they are far apart as in Ara severa, a skeleton of which I have in 
my own collection, as well as in other species of that genus. 
A t the base of the cranium the foramen magnum is seen to be circular in 
outline as it is in most parrots. In Ara it may occasionally approach the 
cordate form, but in a specimen in my collection it is quite circular. The 
temporal wings of the exoccipitals in Palaeornis are only fairly well de- 
veloped, not as much so as in Amazona, and very much less than in Ara 
cMoroptera, where they are very conspicuous, thin, projecting plates of bone 
standing out far behind the cranial base. They are not quite so prominent 
in some of the smaller species of macaws. These latter birds also have the 
presphenoid strongly compressed transversely, with its lower border sharp 
and thin. It is also sharp in Palaeornis, but it at once becomes broader 
above ; and in all Psittaci thus far examined by me, the interorbital septum, 
is thick and never perforated by a central or other vacuity. 
Either p^ery^oifZ is a long, straight, delicate bar, and, as in other parrots, 
these bones meet each other anteriorly, while the articulation with either 
quadrate is on a small, subcircular facet, situated at the infero-distal end of 
the single, convex, transversely flattened facet for the mandible. I may say 
here that the orbital process of a quadrate is, as usual in these birds, a 
pointed and much aborted spine. 
As usual, the palatines are broad, plate- like bones, with their extensive 
mesial surfaces nearly parallel to each other. Their form has been 
previously described by me in my above-cited papers for Conurus and other 
species, and they agree in this African species in their main characters. It 
is to be noted, however, in Palaeornis that anteriorly the mesethmoid projects 
much further beyond the interpalatine articulation than it does in Ara and 
other species. 
With respect to the morphology and arrangement of the ethmoid, 
maxillo-palatines, and other bones forming the walls and enclosures of the 
rhinal chamber, Palaeornis docilis agrees essentially with other Psittaci, apart 
from a few generic departures that pertain especially to it as a species. It 
lacks the peculiar, wing-like extensions of the maxillo-palatines seen in the 
