FEATHERS OF BIRDS. 9 



this means that they were the original primitive form of feathers is another 

 question, and one to which we still need an answer. Embryology might lead 

 us to believe that contour-feathers are modified from some other kind, but 

 there can be no question about the most unique of known birds, Archaeojp- 

 teryx, having possessed true and well-developed contour-feathers. A contour- 

 feather consists of at least three, sometimes four, parts — the <2uill, the ahaft, 

 and the varies, and frequently the aftershaft. The quill is a short, more or 

 less empty, horny tube, generally cylindrical but tapering at each end. At 

 the end, imbedded in the skin, there is a minute opening through which, when 

 the feather was young and growing, blood-vessels passed; but in fully-formed 

 feathers there are no such vessels. It is to the lov>'er end of the quill that the 

 above-mentioned subcutaneous muscles are attached. At its outer end the 

 quill passes uninterruptedly into the shaft, which is solid, opaque, and gener- 

 ally squarish in cross-section. It is often very much flattened, and forms a 

 prominent part of some scale-like feathers. In other cases it is greatly elon- 

 gated and becomes filamentous. The vanes are placed on opposite sides of the 

 shaft and are made up of narrow plates called harhs, which are attached by the 

 broader end to the shaft. They are placed so that the narrow edge is visible 

 while the broad side is generally concealed by the corresponding surfaces of 

 adjoining barbs. The angle which the barb makes with the shaft is usually 

 less than a right angle, and is least nearest the tip of the feathers. The barbs 

 of a contour-feather, except at the base of the shaft, are connected with each 

 other by smaller barbs of the second order known as iarhules, which stand at 

 an oblique angle to the barb, and on both sides of it, in the same relative posi- 

 tion as the barbs and shaft. These barbules taper rapidly to a fine point, but 

 are flattened laterally, and are long enough to cross several barbs obliquely. 

 They thus make the vane, a true net-work or wvJ as it is sometimes called, and 

 hold the barbs together with considerable firmness. In many feathers, the 

 lower edge of the barbules is fringed with little hooks, which are called har- 

 hicels, and which assist very much in holding the vane together. Feathers in 

 which the shaft is stiff, and nearly the whole vane closely webbed by barbules 

 and barbicels, are called pennaceom, while those in which the shaft is more 

 flexible, and the barbs not united, are generally known as plumulacemhs. 

 Most contour-feathers are plumulaceous at the base for a greater or less dis- 

 tance. Strictly pennaceous feathers never have an aftershaft, but the other 

 contour-feathers of the vast majority of birds have one, more or less well- 

 developed. It is interesting to note that aftershafts are wanting in Ostriches, 

 Rheas, Albatrosses, the Steganopodes and Lamellirostres (with few exceptions), 

 Pigeons, American Vultures, Owls, Cuckoos, Kingfishers and the Osprey. 

 An aftershaft is a more or less well-developed shaft with vanes arising from the 

 base of the true shaft close to the quill, and on the lower side. In Cassowaries 



