158 Jeffries on tJic Primaries of Birds. 



feathers more or less modified. Here it is only necessary to note 

 that since all feathers are in quincunx order, they hear definite 

 relations to each other. 



The feathers of the anterior edge run in two or more rows 

 along the fore-arm and hand, certain ones being modified to form 

 the spurious wing. Since these are continued to the very tip of 

 the index finger they often fall into rank with the primaries and 

 coverts of the opposite aspect, and hence can not be distinguished 

 by their geometrical relations from the primaries and coverts. 

 They can he distinguished from primaries, however small, by their 

 relations to the finger bones. The primaries are always on the 

 so-called flexor face, the feathers of the anterior surface are on tin- 

 opposite face. As a rule these two surfaces are separated by 

 the tip of the index finger, which, generally, projects, and in 

 young Ducks bears a claw. 



There is no positive distinction between any of the feathers as 

 regards structure and shape. The feathers of the upper and 

 lower surfaces gradually shade into the primaries. Professor 

 Baird has endeavored to distinguish the primaries from the coverts 

 by their colors. Hut Dr. Coues has shown that the difference in 

 color, when present, does not always separate the coverts from 

 thi' primaries, and that in main species there is no difference in 

 color. So we are forced to the conclusion that the only reliable 

 means of determining a primary or other feather is by its position. 

 Allowing that position is the true key to the homology of the wing 

 feathers, it is evident that in all attempts to determine the number 

 of primaries in birds we should begin with the most simple con- 

 dition of the feather : in short, we should study the embryo and 

 fledgeling. The study of these also has the advantage that they 

 are much less specialized than the adult. 



I shall now take up several of the groups of birds represented 

 in North America in relation to the number of their primaries, 

 considering the young whenever they have been procurable. 



Oscincs. In a young nine-primaried bird, as Melospiza melo- 

 da, nine nearly equal conical papillae will be seen on the posterior 

 edge of the hand, and besides these a much smaller one on the 

 extreme tip of the wing. These are the papilla' of the nine de- 

 veloped and the rudimentary primary. Immediately above these 

 on the dorsal surface are nine small points projecting from the 

 skin between the bases of the primaries : these are the papilla- of 



