74. OSTEOLOGY [Parr IT. 
greater transverse diameter of the internal, and by the greater breadth of the external condyle 
which is flat, or slightly convex, and subcircular. In the Vulturide and Cathartes, the latter 
is narrow and sigmoidal; convex in front, concave behind longitudinally, and rounded trans- 
versely. In Cathartes the inner condyle is grooved at the base externally ; and the trochlear 
ridge is more oblique than in ordinary Pigeons. In the Dodo, its form is similar to that in 
the typical genera of the Columbide, and differs from that in the large Vultures, with which, 
from a correspondence in absolute size, it may be more readily compared. 
The absence of the posterior superior condyle in the typical Rasores, and its presence in 
Pterocles, approximates, so far, this aberrant genus to the Columbide. 
VIII. The subtriangular body of the prefrontal is dove-tailed between the nasal bone and 
antorbital process of the frontal, which advances along its outer edge to the lacrymal groove ; 
in the adult it is anchylosed to these bones above, and internally to the highly developed ale 
of the ethmoid; the prefronto-ethmoidal fissure being in most Pigeons wholly obliterated. 
In Goura, a slender style separates its inner margin from the nasal, so that it is inserted by 
gomphosis, into a deep semi-elliptical notch on the broad antorbital process. It is not subject 
to removal by maceration, or such forces as would almost inevitably break off the upper 
mandible ; and its occurrence in the fractured cranium of the Solitaire, may be regarded as 
presumptive evidence of the Columbine affinities of that extinct form. 
In Pterocles, the prefrontal is anchylosed, but I have not been able to ascertain its 
relation to the antorbital process ; from the narrowness of its frontal aspect, it is not probable 
that this process extends along its outer margin. In the typical Rasores, the prefrontal is 
free, and projects greatly outwards ; its inferior process is reduced to a slender curved style ; 
and the als of the ethmoid are wanting, while in Pterocles they are greatly developed, and 
the prefronto-ethmoidal fissure is obliterated. The prefrontal is unanchylosed, even in the 
adult, in all raptorial birds, except the aberrant genus Cathartes; the free external angle 
supports the os superciliare ; the prefronto-ethmoidal fissure is large and persistent ; and the 
antorbital process forms only a shght angular separation, between the shallow notch lodging 
the apex of the prefrontal, and the deeply concave superciliary margin, which sweeps 
rapidly outwards and downwards to the post-orbital process. 
In Cathartes, the prefrontal is firmly united to the cranium; the supra-orbital mem- 
brane is completely ossified, and gives increased breadth to the forehead. The olfactory 
foramen opens into the apex of the infundibular turbmated ala of the ethmoid; the inferior 
ala is anchylosed to the prefrontal below, but the prefronto-ethmoidal fissure remains. 
IX. The size of the crotophyte impression, although variable in different species, according 
to the resistance to be overcome, is very minute when compared with that in the Vulturidee, 
or even Cathartes; in the Dodo it is exceedingly small, and is not compensated by an 
increase in the area of the internal temporal surface. 
X. The great extent of the digastric impression in Pigeons and in the Dodo, is well 
contrasted with its small size in raptorial birds. The Rasores in this respect, as might be 
anticipated, resemble the Columbide. 
