242 FEA THERS 



feathers consist of a series of flattened and comparatively thick 

 compartmQnts (see Colour). The distal part of the rami is often 

 broadened and modified into a blue -producing structure, bearing 

 no cilia. The rhachis of some of the median rectrices of certain 

 Birds-of-Paradise, the Lyre-bird, and others, has no Aveb, and 

 consists of the shaft alone, while the same applies to the rictal 

 bristles of most birds and the eyelashes of those that possess them, 

 and to the peculiar strong and black quills of the Cassowaries' wings. 

 The expanded tip of the shaft of some feathers which gives the 

 Waxwing its well-known name, and the similar structure of the 

 neck -hackles of some Gallinm, are sjiecial modifications. Nitzsch 

 having stated [Pterylographie, p. 17; Engl. ed. p. 13) that the 

 Contour-feathers of Struthio and Rhea have no cilia or hamuli, and 

 that radii ^ are wanting on some of the rami in Casuarius and 

 Dromxus, the assertion has been often repeated as shewing an 

 important difierential character between Carinatx and Puititse, and 

 assigning a more primitive stage to the plumage of the latter. But 

 Fiirbringer has pointed out (Beitrdge, p. 1482) that the statement 

 needs considerable qualification. In fact, the remiges of Bhea have 

 numerous though small cilia, some of them even ending in hooklike 

 nodules, while the nestling-feathers are abundantly furnished with 

 well-developed cilia. The double shafts of Dromseus and Casuarius 

 carry rami only on their distal portion, but the more basal rami 

 of both webs bear numerous radii. The same applies to the 

 plumage of the Penguins. We have therefore to conclude that 

 the feathers of the Eatitse and Spheniscidse have undergone a 

 degenerating process through the loss of hamuli, cilia, and occa- 

 sionally of radii — a reduction that is most apparent on the remiges, 

 but finding a parallel in numerous instances of reduced Contour- 

 feathers. 



The " Downs " are almost always concealed by the Contour- 

 feathers, and are smaller, more fluffy, and more numerous. They 

 may be characterized by the absence of hamuli, though generally 

 possessing all the other parts of a typical feather, except that they 

 frequently have no rhachis, in which case all their long rami start 

 at the same level from a short calamus. They thus approach the 

 condition of the so-called nestling-feathers of many birds, and it 

 can hardly be doubted that Downs represent a lower or more primi- 

 tive stage than Contour-feathers, although of course many Downs 

 are elaborate, and highly specialized. A peculiarly modified kind 

 are the Powder-downs. 



The " Filoplumes " consist of a short calamus and a very thin 



hairlike rhachis Math few or no rami. Such feathers are always 



associated with Contour-feathers, close to the base of which one or 



1 There is an accidental misprint in the English version of the passage {loc. 



cit.) of "barbicels" for barbules. 



