324 



BRITISH BIRDS. 



though this merges at its base with the distal ends of 

 the rami of the mesoptyle by which it is thrust out. 



In the down-feathers of the trunk, being somewhat 

 older and more advanced, the jjrotoptyles, have been split 

 up. During this process many of the rami have been lost, 

 but many remain attached to the mesoptyle rami. 



The protoptyles are much smaller feathers than those 

 of the succeeding generation, but structurally do not 

 appear to differ in any important particulars. Both 

 generations indeed are in a degenerate condition. 



f^oto\pH^^ 





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SEMI-DIAGRAMMATIC FIGURE OF THE FIRST AND SECO]Sri> 

 GENERATIONS OF NESTLING DOWN IN THE BARN-OWL. 



My contention is proved, however, that the long down- 

 feathers borne out on the ends of the contour-feathers 

 (teleojjtyles) are down-feathers of the second generation 

 {mesoptyles) . 



The Owls, unhke the Accipitres, have no down-feathers, 

 when adult, hence there are no pre-plumulse. 



