314 REPORT OF NATIONAL MUSEUM, 1890. 



black of the breast, while the upper parts are dark bronzy green. 

 These various hues are so arranged or contrasted that only one of them 

 can be seen at once, every change in the bird's position bringing a 

 different color into view. The most brilliantly colored of our Humming 

 Birds are species of the genera Calypte and Selasphorus, the former 

 having two and the latter four species within our limits, all of them 

 belonging to the western portion of the country. 



The males of the species of Calypte have the whole top of the head 

 of the same brilliantly metallic hue as the gorget, in which respect they 

 differ from all other of our hummers excepting the Selasphorus floresii, 

 which is possibly a hybrid between Calypte anna and Selasphorus rufus 

 or S. alleni. In Anna's Humming Bird (C. anna) the crown and gorget 

 are of a richly burnished crimson, changing to purple or even bluish in 

 certain lights. Costa's Humming Bird (C. costce) is a much smaller 

 species, and has the lateral feathers of the gorget much elongated, the 

 gorget and crown being of the richest violet, changing to purple, blue, 

 and even green. 



The Rufous Humming Bird (Selasphorus rufus) and Allen's Hum- 

 ming Bird (S. alleni) have the gorget of a surpassingly vivid fiery red 

 or metallic scarlet, changing to crimson, golden, and even brassy-green, 

 according to the direction of the light, or glowing like a live coal when 

 viewed from a certain direction. So far as lumage is concerned these 

 two species are very much alike, but S. rufus has the upper parts deep 

 rufous or brick-color, tinged with green on the back, whereas S. alleni 

 is almost entirely green above. The Broad-tailed Humming Bird (S. 

 platycercus) is larger than either of the preceding species, and has the 

 gorget soft solferino-pink, with its lateral feathers not elongated — those 

 of the other two being conspicuously lengthened, as in the species 

 of Calypte. The remaining North American species of Selasphorus, 

 Fioresi's Humming Bird, has not only the gorget, with its elongated 

 lateral feathers, vivid metallic scarlet, but the whole top of the head 

 also; otherwise, it resembles most in color the S. alleni. It is one of 

 the rarest of humming birds, only two examples having been met with, 

 one of them near Bolanos, in Mexico, the other near San Francisco, 



California. 



The Lucifer Humming Bird (Calothorax lucifer) has the deeply-forked 

 gorget of a vivid violet-purple, changing to reddish-purple or blue, ac- 

 cording to the light. It is the only one of our North American species 

 having a curved bill. 



The Calliope Humming Bird (Stellula calliope) differs from all others 

 in having the feathers of the ruff narrowed and strongly individualized, 

 each being snow-white for the basal portion and metallic purple at the 

 tip. 



The three species of the genus Trochilus differ conspicuously from one 

 another in the color of the gorget. In the Ruby-throat (T. colubris) its 

 color is, as the name indicates, a glowing ruby-red. In the Black- 



