152 THE STRUCTURE AND LIFE OF BIRDS chap. 



horny tube that overlies the papilla. Of this tube one 

 side only, as a rule, is much developed, the other, that 

 forms the after-shaft, being stunted. The little pit at 

 the top of the quill is the remains of the aperture 

 through which the pulp once forced its way, extending 

 even to the top of the rachis (U2, fig. 38). 



The pulp retires when the feather is complete, 

 leaving only a few white flakes in the quill to mark 

 its former presence (P). When the feather is to be 

 moulted the papilla revives. 



Varieties of Contour Feathers. 



Contour feathers is a general name for the feathers 

 which are visible on the surface and which shape the 

 bird, to distinguish them from " downs," " thread- 

 feathers," and " powder-downs." 



The name plumes is generally reserved for feathers 

 which are merely ornamental or a protection against 

 cold. They have not that perfect system of inter- 

 locking that makes the wing and tail feathers air- 

 proof. To the great wing feathers, the name remiges — 

 i.e. rowers — is given. Some spring from the hand and 

 are called primaries. The Pigeon has eleven such 

 feathers, six of them attached to the second meta- 

 carpal bone, the rest to the bones of second and third 

 digits. If, as often happens (in the Starling, for in- 

 stance), the outermost is very short, it is called a bastard 

 primary. The " thumb " carries no primary feathers. 1 

 The rest of the remiges, called secondaries and inner- 



1 Sec p. 42 on the question whether this is really the thumb. 



