EXPLANATION OF PLATES 

 All figures of feathers of Circus hudsonius 



PLATE 16 

 Fig. 1. Branched tip of filoplume, showing terminal barbs and bar- 

 bules. X 40. 



Fig. 2. Base of group of filoplumes, showing method of insertion into 

 fibrous tissue of skin. Note that roots of all are distinct from each other. 

 X 40. 



[368] 



