84 OSTEOLOGY [Parr II. 
resilient hinge, formed by the beak and the cranium—the cranio-facial line, at which the forehead rises 
abruptly above the level of the upper mandible, it has the same form, but the anterior and posterior, as well 
as the lateral edges respectively, approach to equality in length. 
Its greatest breadth, corresponding to a line drawn between the lateral rounded angles, about six lines 
in front of the post-orbital processes, is three inches nine lines; anteriorly, it contracts gradually to the 
supra-orbital notches, where it is three inches wide; it continues forwards for half an inch of the same 
diameter, and then rapidly diminishes in width to the anterior edge, which is one inch six lines. 
A little behind its greatest transverse diameter, it presents the deep temporal emarginations, and 
gradually contracts to the notches separating the mastoid from the paroccipital processes, where it measures, 
transversely, two inches nine lines. The median longitudinal diameter, from the cranio-facial line to the 
occipital facet, is two inches nine lines; from the anterior angle of the prefrontal to the most remote part 
of the occipital aspect, is three inches two lines. 
This facet is formed, behind and centrally, by the confluent, short but broad, parietals; posteriorly 
and laterally by the mastoid, presenting the muscular impressions, and extending forwards, so as to enter 
into the composition of the post-orbital process (which in the Emeu and Bustard is formed by a separate 
element) ; anteriorly it is constituted by the abbreviated and coalesced frontals, which are raised by the 
sudden and great expansion of the diploé imto a broadly rounded, interorbital protuberance. The wide 
semi-lunar notch, formed by their combined anterior edges, receives the bodies or frontal plates of the 
nasals, which are abruptly bent upwards at an angle of 45° with the plane of the upper mandible, and 
ascend high on the frontal slope to coalesce with the frontals, the sutures bemg obliterated: the nasals 
appear to be relatively much abbreviated, and to be almost, if not wholly, separated mesially by the broad 
triangular extremity of the nasal process of the premaxillary, which is wedged between them, bemg bent 
upwards in the same peculiar manner. The vacuity left between the nasal bone and the ant-orbital process 
of the frontal, on each side, is filled by the triangular body of the prefrontal ; which is anchylosed externally 
to the ant-orbital process, the latter advancing along its outer edge to the lacrymal groove, as already 
indicated ; internally it is separated from the ecto-nasal limb by a fissure, but its apex is anchylosed to the 
frontal plate of the nasal. On removing the beak, the broad, flat arch is seen, formed by the prolongation 
of the interorbital septum and ‘the turbimated lamina passing out from it, on each side, and curving down- 
wards to meet the prefrontal. 
In the immature condition, the peculiar frontal protuberance of the Dodo would uot be developed, 
and the cranium would present a gentle slope, descending from the vertex (which is somewhat in front of 
the coronal fontanelle, and corresponds internally to the most elevated part of the cerebrum), to the upper 
surface of the mandible. 
The profile would hence resemble that in the skull of the Ca/enas, &e., but would be relatively much 
shorter, from the abbreviation of the frontal: the length of that bone, and more particularly of its orbital 
segment, depends on the extent traversed by the peduncle of the olfactory nerve, ere it terminates in the 
proper nerve-filaments distributed to the sense-capsule (e¢/moid). It protects, as the upper segment of the 
fronto-neural arch, not as the lateral moiety of a divided spine, the anterior extremity of the cranio-vertebral 
tube, and is supported below by the interorbital septum, or centrum, of the frontal vertebra; which is 
excavated and reduced to a thin vertical plate, by the fosse for the reception of the eyeballs and their 
appendages. In the Dodo, from the small relative size of the eyes, the interorbital septum assumes more 
of the ordinary characters of a centrum, and the olfactory capsules retrograde, as it were, and recover their 
primary or normal relation to the cerebral cavity. The attentive study of this singular cranium has enabled 
me to recognise the existence only of ¢dree cranial vertebra, essentially related to the three higher senses. 
