30G . REPORT OF NATIONAL MUSEUM, 1890. 



ingly brilliant, while in another genus, AglceactiSj the whole rump is me- 

 tallic, all the rest of the plumage being devoid of luster. 



With the exception of the genus last mentioned, Humming Birds 

 show the full brilliancy of their metallic colors only when the plumage 

 is viewed toward the direction in which the feathers lie ; * that is, one 

 having a specimen in his hand, must, in order to obtain the richest 

 effect, hold it with the head towards him, the bird itself on the oppo- 

 site side from which the light comes. Ee versing its position relative 

 to himself (but not to the light), the metallic hues disappear or are but 

 faintly discernible. In Aglceactis, however, exactly the reverse is the 

 case, the burnished metallic hues of the rump appearing only when 

 viewed against the ends of the feathers.t 



In more than 99 per cent, of the species of Humming Birds, the color 

 of the primaries is a dull purplish dusky, with very faint metallic lus- 

 ter. So nearly universally, in fact, is this the case, that there appear 

 to be only two conspicuous exceptions, the Sapphire- wing (Pterophanes 

 temmincJci) next to Patagona gigas, the largest of Humming Birds in 

 which all the remiges are a brilliant steel-blue, or in a strong light almost 

 a Prussian-blue color, and the Purple Carib (Eulampis jugular fa), in 

 which their color is lustrous bluish green. In no species of Hum- 

 ming Bird are the primaries parti colored ; and when, as is sometimes 

 the case, the secondaries are of more than one color, the additional color 

 is invariably rufous. 



On the other hand, brilliantly colored tails are very common, and 

 sometimes the gorgeous coloring of this member is unapproached by 

 that of any other birds. The Comet Humming Birds (genus Sappho), 

 for example, have very long and deeply forked tails (see PI. xxi, Fig. 4), 

 of the most glittering brilliant metallic red, each feather tipped with 

 velvety black. The allied genus CyanolesWa has a tail of similar size 

 and shape (PL xxn, Fig. 4), but burnished metallic blue or green, in- 

 stead of red. The genera Augastes, Ghrysuronia, Metallura, and Avo- 

 cettula have the brilliant coloration of the tail most conspicuous on the 

 under surface, which is of a splendid golden bronze or red bronze, ac- 

 cording to the species. There are also other types of coloration affect- 

 ing the rectrices, but they are too numerous to particularize in this con- 

 nection. 



*" In such Humming Birds as I have examined," says Gosse (Birds of Jamaica, pp. 

 94,95), "the iridescence of those portions of the plumage that are changeable, is 

 splendid in the ratio of the acuteiiess of the angle formed by the incident ray and the 

 reflected one. Thus the plumes of the neck of the Man go appear to advantage in a 

 room with a single light, only when the beholder stands with his back to the window, 

 and has the bird before him and facing him. Then the perpendicular baud down the 

 throat and breast, which seems composed of the richest black velvet, is bounded on 

 each side by a broad band of glowing crimson, mingled with violet." 



t The same thing, though to a less degree, is observable in the species of Lampropygia, 

 in which, however, the metallic coloring of the rump is much less brilliant. 



