yi INTRODUCTION. 



Birds which lead an aquatic life have these feathers generally more 

 developed than in others, for the manifest intention of affording 

 additional warmth. 



The feathers intended for flight are, first, the wing quills, which may 

 be divided into primaries (4), secondaries (5), and tertiaries (6). The 

 primaries may be distinguished from all the others by their greater 

 size and stiffness. These arise from the bones of the hand. In 

 number they are usually 10; the first of which is on the second finger 

 joint, the 2nd, 3rd and 4th upon the first finger joint, and the other 6 

 upon the metacarpus. In some songbirds, however, the number is only 

 9, and the first feather is either rudimentary or wanting, but never 

 the longest. Secondaries are those which arise from the forearm 

 and are inserted in the skin on the posterior side of the ulna. They 

 are not so stiff and strong as the primaries, usually shorter than them? 

 more curved and more mobile. The tertiaries are those attached to 

 the proximal end of the forearm, while the scapulars lie over the 

 humerus and scapula. 



The feathers on the upper surface of the wing are mostly deve- 

 loped on the cubitus and commonly designated wing coverts. The 

 greater series (3) cover the base or root of the quills, and in general 

 resemble the quill feathers or primaries, and, like them, are destitute 

 of plumules. The second series, or median coverts (2), are also seated 

 in the fold of the skin behind the arm. The smaller feathers behind 

 this series are the lesser coverts (i). 



Next is the tail, the feathers of which in the majority of birds are 

 12 in number, but there are others with as many as 14 to 18 ; 

 these act in unison with the wing, during flight, and when expanded 

 act as a rudder. The tail is longest in the Rasorial types and 

 shortest in the natatorial and grallatorials. The tail feathers are 

 covered at the base by the upper and under tail coverts. The 

 tail, as the wing, in its structure shows a peculiar organization 

 specially adapted for various purposes. An even tail is very 

 uncommon ; rounded tails are the most prevalent, while the racket 

 tail is exhibited in 2 or 3 groups only as Edolius, or Dissemurus and 

 Dtssemuroides, and the lyre-shaped tail exclusively in the Rasorial 

 order. 



