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two fibule ; the humerus and radius are usually, and the ulna is always, longer and larger 
than their analogues in the hind extremities ; then also there are the two distinct carpal 
bones, a metacarpus and characteristically modified phalanges. The chances were thus 
ereater that the next bone of an extremity discovered in the alluvium of New Zealand 
would have been one of the anterior members, had these been developed to serve as 
wings in the Dinornis. But what is the fact? Eighteen femora, eleven tibiw and six 
tarso-metatarsi, with two toe-phalanges, have been consecutively discovered, and not a 
trace of any part of the osseous framework of a wing: not a fragment of scapula, of hu- 
merus, or of the bones of the forearm or hand. 
The doctrine of chances thus adds its proof, were such required, to the inferences of 
physiological correlation, that the Dinornis had no wings. We may next inquire to 
what extent, short of the faculty of flight, the anterior or pectoral members were deve- 
loped in this extinct genus, with the same confidence in the laws of correlation as a 
guide to the determination of this question. 
The anterior members present very different degrees of arrested development in the 
different existing species of the Struthionide, and always retain, under even their most 
rudimental condition, the characteristic modifications of form and structure by which 
they are adapted to serve the office of flight in ordinary birds. 
Tn these, as is well known, the body is made specifically lighter, and in a direct 
ratio with the powers of flight, by a proportionate extension of the air-cells through the 
muscular and osseous systems. A much greater proportion of the skeleton is permeated 
by air in the Swallow than in the Quail. 
The Rhea and the Ostrich have the largest and most wing-like anterior members of 
all the Struthionide ; they use them to aid in their swift progression: throwing their 
body forwards beyond the centre of support afforded by the hind legs, they partly sustain 
it by the flapping of the curtailed wings, whilst the legs, to the extent to which they are 
thus relieved from the act of sustaining, are free to exert additional force in propelling 
the body; and it may be said of the Ostrich at full speed that half the body flies and 
half runs. Now we find that in these semivolant Struthionide the warm and expanded 
air of the respiratory cavities is freely admitted into the bones of the skull, the vertebre, 
the ribs, the sternum, the coracoids, the pelvis and the femora. 
In the Emeu and Cassowary, whose pectoral members are much reduced in size, use- 
less for anything like flight, and serving, so faras is known, only for some feeble actions 
of defence, the air is less freely admitted to the bones of the trunk, but still penetrates 
the femur. 
In the Apteryx the rudimental wings are so minute, that the fact of their retention of 
the typical structure requires careful dissection for its demonstration : and in this species 
we find the lungs confined to the thoracic-abdominal cavity, and not extended into any 
part of the skeleton. The Dinornis presents an intermediate condition between the 
Apteryx and the Emeu in regard to the extension of the air-cells, which penetrated the 
