lO 



A HISTORY OF BIRDS 



they may give a hoary appearance to the necks of these birds. 

 In some other birds the filo-plumes are distributed as conspicu- 

 ous hair-Hke threads all over the neck and back, e.g., the genus 

 Criniger. 



The rictal bristles 

 of Night-jars and Fly- 

 catchers, and the eye- 

 lashes of many birds, 

 e.g.., Ostriches and 

 Hornbills, appear to 

 be akin to filo-plumes. 

 The significance of 

 powder-down feathers 

 is still more puzzling. 

 These are most per- 

 fectly developed in the 

 members of the Heron 

 tribe, where they form 

 large patches over the 

 breast or thighs. But 

 they occur also in 

 many other birds, not- 

 ably in Parrots and 

 some birds of prey, and 

 in the " Frogmouth " 



T, A TA T^ (Podargus). "Among 



111. 3. — A Developing Filo-plume showing d • u • 



THE Rami which later disappear, and the the Passerme birds 



Main Shaft (f) which remains to form the fj^gy a.re met with onlv 



" FiLo-PLtiMF. " y y 



in the " Wood-Swal- 

 lows" (^Artamns). 

 In the Parrots and Hawks they occur only as sparsely dis- 

 tributed tufts, in other cases in the form of large patches. 

 When examined these feathers are found to consist of a number 

 of barbs matted together, and of an exceedingly friable char- 

 acter, so much so, that they are continually disintegrating into 

 a fine powder which to the touch resembles '• fuller 's-ear th ". 

 The curious bloom, which covers the beak and face of the 

 African Parrot {Psittacns eritJiaais) and the plumage and beak 

 of Cockatoos, is due to this powder. There is a tradition — 

 quite unfounded — to the effect that in the Heron tribe this 



' filo-plume ' 



p = pith-cells. 



T = transient rami. 



