Cu. I.] OF THE DODO. 97 
‘ 
to the former; it extends forwards, contracting to a groove, which leads to the posterior angle of the ramal 
vacuity; behind, it extends upwards to the coronoid edge. 
Having thus given a detailed account of the skull of the Dodo, it now remains to. 
contrast it generally with that of other Pigeons; for this purpose, and to supersede the 
necessity of lengthened descriptions, it has been thought desirable to give in Plate X., figures 
of some of the more remarkable and varied forms of the skull in that family, with a reduction 
of the head of the Dodo for comparison. 
I am indebted to that eminent ornithologist, Sir W. Jardine, for permission to examine 
the bones remaining in the only specimen of the Didwaculus in Europe; and thus I am 
enabled to confirm the opinion expressed by Mr. Gould, regarding the co/wmbine affinities of 
that singular form, by the most certain of all tests, to wit, an examination of its osteological 
characters. 
The most important and apparent difference between the skull in the Dodo and that in the lesser 
forms, depends on the small relative size of the brain and visual organs in the former, and the consequent 
abbreviation of the cranium and elongation of the basal part of the mandible. This difference, though 
readily explicable, might cause many, even, acute anatomists to overlook the family resemblances to that 
of Pigeons in the skull of this extinct bird. The happy appreciation of these by Reinhardt, entitles that 
learned zoologist to a high place among Paleontologists. In Zreron, the extreme length of the cranial 
cavity is nine lines, and in Gowra, one inch two lines; while in the Dodo, it is only one inch nine lines, 
little more than double the length of that cavity in the diminutive Zreron. The outlet (foramen mag- 
num) is also relatively less in the Dodo than in Zreron. (Plate X., Fig. 2 a, 8 a.) 
In the smaller Pigeons, the supra-occipital plate is less vertical and flattened than in the Dodo, being 
more arched transversely, and inclined obliquely backwards. The occipital condyle is less prominent, and 
the basilar protuberances for the insertion of the MW. recti capitis laterales majores less apparent. The 
mesial supra-occipital aperture exists in all; and at an early period, it is very large and not separated by 
bone from the foramen magnum. Reference to the plates will indicate other minor differences, which may 
vary in the species of the same genus. 
The superior facet in the smaller Pigeons is longer and narrower than in the Dodo, and the expansion 
of the frontal diploé less abrupt; the mastoidal angles, bearing the muscular impressions, are also bent 
downwards on the lateral aspects ; while in the Dodo, they are thrown upwards by the great development 
of pneumaticity in the upper part of the lateral walls of the cranial cavity. The supra-orbital border is 
broadly concave and the interorbital region narrowed in ordinary Pigeons, and especially in Geophaps. 
The profile is best seen in the respective figures; the dotted le in the Dodo indicates the probable 
outline before the development of the frontal protuberance. In Zreron and Gowra, there is a foramen as 
in the Dodo, perforating the cranium in the position of the coronal fontanelle; numerous venous grooves 
converge towards it. ‘The form and relative proportion of the different muscular areas vary in the different 
genera; they are most deeply impressed in Zreron. 
In Goura there is a tendency to the development of the frontal protuberance opposite the apex of the 
cerebral cavity, and it is distinctly bilobed, the mesial line being traversed by a deep longitudinal furrow. 
The anterior portion of the coalesced frontals is elongated, as in other Pigeons, in relation to the great 
extent of the interorbital septum: the nasals touch each other in the median line, and their inner limbs 
are in contact with, and ultimately soldered to, the turbinated ale. The hinge formed by the upper 
