428 CORACIIFORMES CHAP. 
even in snowy weather, while Oreotrochilus chimborazo and O. 
pichincha brave the storms of the volcanic regions of the Andes 
of Ecuador, close to the perpetual snow at a height of sixteen 
thousand feet. The forms found in the furthest north and south 
are few, and draw towards the equator at the cold time of year; 
while the successional flowering of insect-attracting plants, and 
the seasonal alteration of the snow-line, cause latitudinal or alti- 
tudinal movements of the same nature. Only eighteen species are 
recognised as occurring north of Mexico by New World ornitholo- 
cists, but many more inhabit Central America, which are either 
peculiar to that region and even its elevated tablelands, or range 
into South America; none, however, being migrants in the strict 
sense of the word. The headquarters of the Family lie in 
Colombia and Guiana, though Venezuela, Peru, Bolivia, and 
Brazil claim many, and some of the finest, forms: on the other 
hand, the dry Peruvian plains and the Argentine Pampas lack 
sutticient insect-food to be favourite residences. With regard to 
the West Indies the numbers increase from the Bahamas to 
Trinidad, each island often having its own species ; Hustephanus gal- 
eritus, E. fernandensis and E. leyboldi occupy the Juan Fernandez 
group, and the first-named Chili and the Straits of Magellan 
also. Humming-birds may be roughly divided as alpine, sub- 
alpine, and lowland, while it may be noticed that comparatively 
few inhabit the great forest-clad delta of the Amazon, the 
congenial centre of so much bird-hfe. 
The Trochilidae live almost entirely in the air, and fly power- 
fully, though seldom to great distances; they will flit from flower 
to flower for hours, darting off to each new blossom with arrow-like 
speed, and remaining suspended before it, with the body vertical 
and the wings in a state of tremulous motion, while probing 
the immost recesses. This is commonly accompanied by a vibra- 
tory movement of the tail, which in some cases opens and shuts 
like a fan. The humming sound, produced at each new depar- 
ture or change of course, and audible for several yards, is due to 
a pulsation of the wings, so rapid that little can be seen of the 
bird but an indistinct misty outline. Messrs. A. and E. Newton 
give the following charming account of Zulampis holoseri- 
ceus*:—“One is admiring the clustering stars of a Scarlet 
Cordia, the snowy cornucopias of a Portlandia, or some other 
1 Ibis, 1859, pp. 139, 140. 
