NESILING FEATHERS OF THE MALLARD. 



635 



That in ancient birds feathers were intimately associated with 

 scales is suggested by the feather papillae having approximately 

 the same arrangement as the scales of reptiles, by feathers 

 emerging from under scales above the tarsal joints of the Wood- 

 cock, and by chicks and ducklings having vestiges of scales in 

 connection with the feather filaments of the legs. In the case of 

 Grouse and other birds >vith only one feather emerging from 

 under a foot-scale, we are tempted to assume that each foot- 

 feather is developed fi-om part of the scale it is associated with. 

 But when we find three feathers projecting from under the foot- 

 scales of the Barn Owl (Strix flammea) and seven or more 

 feather filaments occupying an area equivalent to a foot-scale, we 



Text-fia'ure 12. 



Scale from the foot of the small Argentine Armadillo {Chlamydopliorus) from under 

 which pi-oceed a number of hairs developed from the skin underlying the scale. 

 The three filaments proceeding from under the foot-scales of Barn Owl embryos 

 like the hairs associated with the scales of mammals are developed from the 

 skin under the scales and not by a splitting of the scales or from fragments of 

 the scales. 



are less inclined to admit that each of the foot feathers of Grouse 

 corresponds to part of a scale. When the developi^ent of the 

 foot feathers of the Barn Owl is studied, one large and two small 

 filaments are found projecting from many of the scales ; the large 

 filament contains a protoptile, and each small filament contains a 

 prefilopluma. Similar groups of filaments which occur above the 

 tarsal joint are overlapped by scale vestiges, but in the three 

 feather groups on the head scales are conspicuous by their 

 absence. The well-developed scales in connection with the foot- 

 feathers and the vestiges of scales in connection with feathers 

 above the tarsal joints support the view that birds, to start with, 

 had a complete scaly covering and a sparse coat of feather filaments. 



