Iv HUMMING-BIRDS 337 
the interesting fact that the latter are essentially swifts— 
profoundly modified, it is true, for an aerial and flower- 
haunting existence, but still bearing in many important 
peculiarities of structure the unmistakable evidences of a 
common origin.? 
1 Recent researches into the anatomy of the swifts and humming- birds 
have brought to light so many and such important differences that the above 
conclusion, founded on comparatively superticial characters, becomes doubtful. 
Dr. Shufeldt considers that both groups are so isolated that they each require 
to be classed as a distinct order of birds. But while the swifts are believed 
to have undoubted though remote affinities with the swallows, it cannot yet 
be determined whether they have any real affinity with the humming-birds, 
which latter appear to have no special and unmistakable relationship with 
any other order or family of birds. See “Studies of the Macrochires, Mor- 
phological, and otherwise, with the view of indicating their relationships,” etc., 
by R. W. Shufeldt, M.D., in the Journal of the Linnean Society, vol. xx. ; 
Zoology, pp. 299, 394: 1889. 
