252 Zoologica : N. Y. Zoological Society. [I ; 13 



In a bird shot about two months later, in mid-November, 

 the tips had disappeared, leaving 2 to 5 mm. of strong, bare, 

 projecting rhachis (Fig. 98, D). Even if there were no dis- 

 tinction of color or pattern between this plumage and that of the 

 adult, the two could be told by a glance at the tail-feathers; 

 those of the younger plumage showing unfinished, broken tips, 

 while in the succeeding rectrices the shafts end in a delicately 

 graduated point, clothed to the very tip with barbs (Fig. 98, E). 



The Torrent Ducks are of interest in this respect, as show- 

 ing that what in other members of the family is merely an 

 evanescent physical connection between two series of feathers, 

 has in this case been carried to a much greater extreme of spe- 

 cialization, probably of direct benefit to the species. 



