72 PROFESSOR OWEN ON THE 
wielding of long, powerful, massive mandibles, serving most probably to enable the bird 
to subsist on some proportion of animal diet, in addition to such vegetable food as it 
might gain from the ground, Such indiscriminate feeding doubtless rendered its flesh 
less palatable than that of the winged Pigeons of the Mauritius to the Dutch navigators 
of the sixteenth and seventeenth centuries. 
But the affinities of Didus will be more fully and decisively brought out in the com- 
parison of the, in this respect, more instructive and light-giving parts of the skeleton. 
§ 10. Comparison of the Skeleton. 
The dorsal region of the vertebral column shows, in some birds, a confluence of 
certain vertebre: I have observed four to be so welded together by both centrums and 
neural spines in Phenicopterus, viz. the second to the fifth dorsal inclusive, leaving the 
sixth free, which articulates with the first costigerous sacral vertebra. In Platalea 
three dorsals coalesce in advance of the antepenultimate free vertebra. In the smaller 
diurnal birds of prey five dorsal vertebre are usually confluent, leaving one free vertebra 
for the lateral movements of the trunk between such dorsal “ sacrum” and the pelvic one. 
In Vultures, Plovers, Bustards, Cranes, Psophia, Cariama, Palamedea, the Penguins, and 
in all flightless land-birds save the Dodo, no such anchylosis takes place. The Colum- 
bide are the species in which thé dorsal vertebra, homologous and the same in number 
with those of Didus, undergo the process of confluence into one mass of bone: they are 
the three which immediately precede the last (moveable) dorsal vertebra; and of these 
the two anterior develope, in Gowra and Didunculus, hypapophyses closely corresponding 
in shape and proportion with those in the Dodo. 
The chief difference which Didus offers in the present region of ‘the vertebral column 
from that of Columbide is in the greater number of the vertebrae or segments which 
are typically completed by bony heemapophyses articulating with pleurapophyses and 
directly with their mass of coalesced and expanded hemal spines constituting the ster- 
num. Of these typical thoracic segments there were five in Didus (Pl. XV.) ; Didun- 
culus (ib.) shows four; Goura three. In both existing genera these segments are suc- 
ceeded by a single one, anchylosed to the fore part of the sacrum, but with the pleura- 
pophysis long and moveable, with its hemapophysis terminating in a point before 
reaching the sternum, and extensively connected with the antecedent hemapophysis or 
sternal rib: in both genera two dorsal vertebre in advance of the typically complete one 
have moveable pleurapophyses terminating freely in a point, with no hemapophyses 
other than the costal processes of the sternum may represent. In Gowra, which has six 
pairs of moveable or thoracic ribs, the second pair belong to the first of the three anchy- 
losed dorsal vertebree: in Didunculus, which has seven pairs of thoracic ribs, the second 
pair belongs to the free dorsal immediately in advance of the anchylosed mass. Sup- 
posing Didus to have had one pair of ribs behind, and two pairs in front of those that 
directly articulate with the sternum, as the vertebra Pl. XVII. fig. 7 indicates, it 
