Cu. IT.] OF THE SOLITAIRE. 119 
so that the bone is more acted on by atmospheric agencies at these places; and a small piece of the 
lower node is removed (Plate XV. Fig. 2a, 24). The orifices of the minute periosteal Haversian canals 
are more distinct than usual, and give the surface a granular aspect. The parietes of the shaft in the 
immature specimen (74. Fig. 4) are nearly one line thick; the medullary canal is divided, as usual, into 
three compartments by two thin partitions, which diverge as they pass from the anterior to the pos- 
terior wall; the cancellated tissue extends farther towards the middle of the shaft, in the narrow lateral, 
than in the wide central division. 
We have now ascertained that the cranium of the Solitaire resembles that of the Dodo in numerous 
important points, differing in such respects only, as would justify us in regarding these birds as specifically 
distinct. The metatarsus, also, is principally distinguished from that in the Dodo, by such variations in size 
and proportion as might occur in species of the same genus. But in a small family, the members of which are 
confined to distinct localities, we are warranted from analogy, in regarding each as forming the type of a 
genus. The marked dissimilarity in external form between the Dodo and Solitaire, and the position of the 
caruncular ridge in the latter, together with the shorter beak, fully justify the establishment of another genus 
(Pezophaps) in the Didine, to include this lost form. That the Dodo and Solitaire belong to the same extinct 
sub-family of the Colwmbide, characterized chiefly by the peculiar structure of the cranium and rudimentary | 
condition of the wings, no one will, we trust, doubt, who has carefully and impartially examined the evi- 
dence ; the discovery of the osseous remains of the other extinct birds, supposed to belong to this group, 
will enable us more strictly to define its boundaries, and its alliances with the other sub-families of the Order 
Columba. We regard the Dodo, and its affine the Solitaire, as terrestrial flightless modifications of the Zrero- 
nine sub-type, but having no immediate affinity with the other ground Pigeons, as Gowra, Calenas, &c., 
which are more directly allied to the ordinary Columbine. 
For the reception of that modification of the Zreronine sub-type, represented by the Didunculus, we 
propose to establish the sub-family Gnathodontine, in the hope that other members of the group remain to be 
discovered in the Polynesian Islands. The Gnathodontine are connected to the Treronine by the sub-genus 
Toria, which differs from the typical Zreron in the abbreviation of the mandibles, and in the pseudo- 
raptorial form of the upper gnathotheca. The Didwnculus is essentially a perching bird, but terrestrial 
affines probably exist, or have become extinct like the Dodo and Solitaire. The Pigeons form a perfectly isolated 
group of birds, having no direct affinity either with the Jasessores or Galline. The rasorial genus Péerocles 
approaches the Pigeons in the structure of the cranium, and in the form of the metatarsus; but it is desti- 
tute of the peculiar co/wmbine cere, and the hind toe, when present, is rudimentary and elevated. The 
Galling, then, approach the Pigeons through Péerocles, but no fusion of these groups is thus effected. 
From other considerations, the Prince of Canino and Col. Sykes had, also, previously recognised the ap- 
proximation of Pterocles to the Columbide. The peculiar cere, and the great development of the nasal scales, 
are characteristic of the Coldumbcde, and probably have some relation to the mode in which the nestlings 
are nourished. A milky fluid, analogous to the lacteal secretion in Mammalia, is elaborated by the thick- 
ened mucous membrane of the crop of the parents, and poured into its cavity, where it mixes with the mace- 
rating ingesta, and the young of certain species thrust their beaks into the throat of the parent, to obtain 
the food thus provided. 
