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 {Archseopteryz). 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 Keptiles 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 Eemiges of the Ostrich nor the vane-less quills of 

 the Cassowaries could ever have produced their typically " Neor- 

 nithic " wing-skeleton.^ 



^ As bearing on this important subject the following references may be of 

 use : — E. Alix, "Sur les plumes ou remiges des ailes des Oiseaux," Journ. 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 

 Oscines," 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. 3 (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 batarde dans les Oiseaux," Rev. Mag. Zool. 1872, p. 83 ; A. R. 

 Wallace, "On the arrangement of the Families constituting the Order Passeres," 

 Ibis, 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 course the great works 

 of Nitzsch and Prof. Fiirbringer. 



