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ON THE CLASSIFICATION OF BIRDS. 



(76.) The spurious quills are constructed precisely 

 the same as the others. Their number coincides ex- 

 actly with those of the primaries, that is, ten ; but they 

 are of so many different lengths, that no author has yet 

 determined either their number or their office. Taken 

 collectively, they assume the shape of a somewhat ir- 

 regular fan, the two first being very small, the third 

 and fourth longest, and the rest diminishing in length 

 until they become equal to, and join with, the greater 

 covers ; they are remarkably stiff, considering their short- 

 ness, and they are unquestionably intended to strengthen 

 and cover the base of the ten primary quills, as being 

 those which are the most important to the power of 

 flight, and require the most effective support. The 

 greater wing covers, in fact, do not cover the greater 

 quills, but merely the lesser ; for, as they approach the 

 greater, they take a curved direction, and merely reach 

 sufficiently far to lay over the base of the spurious 

 quills. 



(77») The formation of the wing, in reference to 

 its office, depends almost entirely upon the arrangement, 

 the proportion, and the shape of the quills ; and these 

 again determine the powers of flight. The three sub- 

 jects are thus so intimately connected that they will lose 

 their chief interest unless they are treated of together. 

 Between a swallow and a turkey, the most familiar in- 

 stances that can be adduced of the rapidity and the 

 difficulty of flight, there are innumerable modifications 

 of the same power, the most striking of which will 

 alone be noticed. The greatest powers of flying are 

 enjoyed by the different groups which belong to, or 

 represent, the natatorial order, to which alone those 

 birds are confined which catch their food in the air. 

 The albatrosses, frigate-birds, and petrels, are conse- 

 quently the most expert flyers in the feathered creation. 

 In the fissirostral tribe, which is the natatorial type of 

 the perchers, we see the same faculty given in a pre- 

 eminent degree to the swallows, swifts, night-jars, and 

 bee-eaters ; and in this manner we may trace the same 



