PEATHEES 



11 



The only explanation, so far as I am aware, of this 

 remarkable state of affairs is contained in a suggestive paper 

 by Degen.' Degen commences with the assumption that in 

 the hands of the primitive bird all three fingers — then freely 

 movable — were furnished with remiges. In modern birds 

 remiges are only attached to the 'thumb {ala spuria) and to 

 digilQJ/ Degen also postulates a fourth finger (of which 

 rudiments have been discovered in modern birds ; see below) 

 with its remiges. 



When the metacarpal bones became fused the feathers 

 of the third and fourth digits were, he supposed, forced back 

 3 4 (5) 6 



-Ji 



Fig. 2.- 



-n.c 



VI 



-a. Cubital Bemiges of Pheasant. 6. Cubital Remises 

 OF Golden Eagle (afteb Wbay). 

 R 1-7, remiges ; i).(7, dorsal tectrix major \ Ul, ulna. 



// 



'- - nc 



upon the ulna, as there was no longer any room for their 

 coexistence with those of the second digit upon the com- 

 pressed hand. Among these the carpal remex was also 

 pushed back. As this remex was attached to an unstable 

 bone or cartilage, its position was not secured, and the varia- 

 bility remained when the feather altered its position ; hence 

 the presence or absence of the fifth remex, which is this 

 feather. 



The carpal remex is another variable feather. It is present 



' ' On some of the Main Features in the Evolution of the Bird's Wing,' Bull. 

 Brit. Om. Club, July 1894 (published in Ibis). See also for quincubitalism 

 Gebbe, ' Sur les Plumes de Vol et leur Mue,' 

 p. 289. 



Bull. Soc. Zool. Fr. ii. 1877, 



