THE SKULL OF BIRDS
The Skull of Birds ([Fig. 65]).—If, because it is less important from the artistic point of view, we do not consider it necessary to describe in detail the skull of birds, we yet think it useful to indicate, in their general lines, the peculiarities it presents.
Fig. 65.—Skull of the Cock: Left Lateral Surface.
1, Occipital bone; 2, parietal bone; 3, frontal bone; 4, ethmoid bone; 5, cavity of the tympanum; 6, quadrate bone; 7, superior maxillary bone; 8, malar bone; 9, nasal bone; 10, 10, intermaxillary bone; 11, nasal orifice; 12, os unguis or lachrymal bone; 13, inferior maxillary bone.
In this group the skull is generally pear-shaped; to the cranium, of which the bones are arranged in such a way as to give it a form more or less spherical, succeeds a face more or less elongated, according as the bill is more or less developed.
In general, the bones of the skull coalesce very early, with the result that it is only in very young individuals that we can determine their presence.
We find the skull to consist of an occipital bone, two parietals, a frontal, etc.; we will indicate but one detail in connection with these bones: it is the presence of a single condyle for the articulation of the occipital bone with the atlas. We also note the quadrate bone, which is situated on the lateral part of the cranium, is movable on this latter, and acts as an intermediary between it, the bones of the face, and the lower jaw. The quadrate bone is regarded as a detached portion of the temporal; on the signification of this we do not now propose to dwell.
On the anterior portion of the face we find the nasal bones, which, articulating with the frontal on one side, circumscribe, on the other, the posterior border of the nares. The nasal bone of the one side is separated from that of the opposite by the intermaxillary or premaxillary bone, which forms the skeleton of the superior mandible.
The superior maxillaries, which are rudimentary, are situated on the lateral parts, and prolonged backward by an osseous style which articulates with the quadrate bone; this styloid bone, the homologue of the malar, is designated by certain authors as the jugal or quadrato-jugal bone.
It is with the quadrate bone also that the inferior maxillary articulates.