REMIGES 781 
Natural Selection, just as the scales on the hind margin of Turtles’ 
paddles are elongated and flattened out. Subsequently their 
lengthening and strengthening extended to the feathers of the 
metacarpus and so on to the digits, which at this stage were still 
free (Archxopteryx). If these ancestral Birds possessed a patagium 
or duplication of the skin which would assist as a parachute, it was 
gradually restricted to the proximal region between the fore limb 
and the trunk, or it might interfere with the folding of the limb 
now become a wing. Already in the Reptiles the PoLLEX had 
shewn a tendency to shorten, and it remained outside the series of 
the other fingers, taking part only to a slight extent in the forma- 
tion of the wings. The metacarpals became elongated and 
coalesced because of their simultaneous and one-sided use. The 
other bones of the mid-hand and of the fifth, fourth and in part 
of the third digits were reduced in size and number, since the 
newly-gained and much-strengthened axis required their presence 
the less, and moreover the full development of those digits 
would have hindered the folding of the wing, which is effected 
by a strong abduction towards the ulnar side. From purely 
mechanical causes the primaries grew into quills stronger and larger 
than the cubitals. In the embryos of many Birds the Remiges of 
the forearm appear earlier and for some time grow more rapidly 
than those of the manus, until they are overtaken by the primaries 
—thus repeating their phylogenetic development. 
After the reduction and partial ancylosis of the bones of the 
manus have once taken place it is as impossible to free or separate 
the coalesced metacarpals again as it is to restore the lost digits. 
Neither the soft Remiges of the Ostrich nor the vane-less quills of 
the Cassowaries could ever have produced their typically “ Neor- 
nithic” wing-skeleton.! 
1 As bearing on this important subject the following references may be of 
use :—E. Alix, ‘“‘Sur les plumes ou rémiges des ailes des Oiseaux,” Jowrn. Soc. 
Philomath. 1874, p. 10; J. Cabanis, ‘‘ Ornithologische Notizen,” Arch. /f. 
Naturg. xiii. (1847), pp. 16, 256 ; E. Coues, ‘‘ On the number of the primaries in 
Qscines,” Bull. Nutt. Orn. Club, i. p. 60 (1876); H. Gadow, ‘*‘ Remarks on the 
numbers and on the phylogenetic development of the Remiges of Birds,” Proc. 
Zool. Soc. 1888, p. 655; J. G. Goodchild, ‘‘ Observations on the disposition of 
the cubital coverts in Birds,” op. cit. 1886, p. 184; J. A. Jeffries, ‘‘On the 
number of primaries in Birds,” Bull. Nutt. Orn. Club, vi. p. 156 (1881); W. P. 
Pycraft, ‘‘ Contribution to the pterylography of Birds’ Wings,” Trans. Leicester 
Lit. and Philos. Soc. ii. pt. 8 (1890) ; C. J. Sundevall, ‘“‘Om Foglarnes vingar,” 
K. Vet.-Ak. Handl. 1843, p. 303 (Engl. transl. Ibis, 1886, p. 389); J. Vian, 
“De la plume bitarde dans les Oiseaux,” Rev. Mag. Zool. 1872, p. 83; A. R. 
- Wallace, ‘‘On the arrangement of the Families constituting the Order Passeres,”’ 
bis, 1874, p. 406; R. S. Wray, ‘‘On some points in the morphology of the 
wings of Birds,” Proc. Zool. Soc. 1887, p. 343; with of ccurse the great works 
of Nitzsch and Prof. Fiirbringer. 
