THE BXTEBNAI STErOTTJBB OF BIEDS. 1 57 



They are divisible into two sets, namely (A) those which 

 spring from the pinion and cover the primary remiges, and (B) 

 those which cover the secondary remiges. 



(A) The wp'per 'primary coverts spring from the pinion and 

 overlie the primaries. By these it can often be determined 

 how many primaries a Bird has. There is a series of large 

 size, and a second series mostly few in number and scarcely 

 visible, being covered almost always by the bastard wing. 



(B) The coverts of the second category, or the v^er 

 secondary coverts, mostly spring from the fore-arm, and are 

 divided into three distinct categories or transverse rows : — 



(1) The greater upper secondary coverts (tectrices majores) or 

 " greater coverts." This category includes the largest and most 

 important set of feathers of all the " upper secondary coverts." 

 They form the transverse row which extends farthest down 

 over the secondaries, and afford valuable characters for classifi- 

 cation. 



(2) The median upper secondary coverts (tectrices mediae), or 

 middle coverts, are a transverse row of smaller feathers which 

 cover over the bases of the greater coverts. Their apices are 

 often otherwise directed than those of the latter. 



(3) The least upper secondary coverts (tectrices minores), or 

 lesser coverts, are all the feathers, forming various transverse 

 small rows, which cover over the bases of the middle coverts 

 and the upper surface of the wing — fore-arm and fold of skin, 

 or patagium, attached to it — thence to its anterior margin. 



The humeral coverts are a short series of feathers arising 

 from the skin over the humerus, very well seen in the Duck. 

 These coverts are very often absent, and when present they 

 may have much of the appearance of innermost secondaries, 

 as in the Duck, where they are very long and conspicuous. It 

 may also, in some cases, be difficult to distinguish them from 

 " scapulars," but they take origin from the skin over the 

 upper-arm bone, more or less external to the humeral pteryla 

 where it gives origin to the scapulars. These two categories 

 of feathers — scapulars and humeral coverts, can both be seen 

 very clearly and distinctly in the Duck. 



The under wing-coverts (tectrices inferiores) are divisible into 

 primary and secondary ones like the upper wing-coverts, but. 

 they are less important for purposes of classification. 



Some of these feathers may, however, be distinguished as 



