Henshaw oti Selasphorus alleni. 13 



of the earlier and, as a rule, far less particular compilers. The 

 particularly narroiu outer rectrices mentioned in all the accounts, 

 upon which so much stress is laid by Mr. Elliot, by no means 

 necessarily refers to the Green-backed form, though, as a matter 

 of fact, the outer tail-feathers are much narrower in this species 

 than in the other. The term is evidently one of contrast, the 

 comparison being suggested by the extreme narrowness of the outer 

 feathers as compared with the inner, which are really very broad. 

 In fact, there was nothing else to invite this particularity here. 

 There being but one species known to all these authors, there was 

 hence no need of comparative diagnosis other than that suggested 

 by the parts themselves. 



Gould, in his Monograph of the Trochilida; after describing what 

 was unquestionably the true Rufous-backed bird of Gmelin, the 

 male with its " back cinnamon brown," adds : " The above is the 

 usual coloring, but I have occasionally seen fully adult males with 

 the rich gorget in which the coloring of the back was totally (lif- 

 erent, being of a (/olden green* and presenting so great a contrast 

 as almost to induce a belief that they were of a different species." 

 This latter allusion, as in the case of Professor Baird's, is without 

 doubt to the Green-backed form, its peculiai'ities of color being evi- 

 dently the only difference noted by him. His figures, it is true, 

 do not show the notched rectrix belonging to the Rufous form, 

 whence Mr. Elliot concludes that they must represent the other bird. 

 But in color, as also, it is to be particularly noted, in the shape and 

 size of the outer rectrices, they correspond exactly with the Rufous- 

 back and differ irreconcilably from the Green-back. In short, they 

 would not serve to identify the latter bird at all, but are good figures 

 of the former in all respects except in the omission of the notch in 

 the tail-feathers, in which particular they merely repeat the over- 

 sight of the other authors. 



The Smithsonian possesses several specimens of the Rufous-backed 

 form with its notched tail-feathers received directly from Mr. Gould. 

 That his collection contained this form is therefore certain, if in- 

 deed further confirmatory proof were necessary. The peculiarity 

 of the notched tail-feathers was simply overlooked. 



But to return to the earlier writers ; the selection of Gmelin's 

 name is of itself suggestive that the bird he had in hand could 



* Italics my own. 



