242 Birds of Colorado 
structure. The following are the external characters, 
which, however, are sufficiently vague: Bill either 
very short and depressed with a very wide and deeply 
cleft gape, or very long and slender, far exceeding the 
head, but never with a cere; wings very long with ten 
primaries and tail with ten rectrices ; feet always small 
and weak. 
Key OF THE FaMiqies. 
A. Bill short, broad and depressed, but gape very large. 
a. Plumage lax and soft; claw of middle toe pectinated. 
Caprimulgide, p. 242. 
b. Plumage firm and hard; claw of middle toe not pectinated. 
Cypselidz, p. 248. 
B. Bill very long and slender, gape not deeply cleft; plumage 
more or less metallic. Trochilidz, p. 251, 
Family CAPRIMULGIDZA. 
Head broad and flat, bill very small, depressed, tri- 
angular in shape from above, but the gape extending 
back to below the eye, and with usually a great 
development of the rictal bristles ; wing moderate, the 
secondaries never so short and reduced as in the Swifts 
and Hummers; legs short and weak, the claw of the 
middle toe pectinated along its inner margin. 
This family contains the birds known as Goatsuckers 
or Nightjars in the Old World, Whip-poor-wills in the 
New ; they are further distinguished by their soft, lax 
plumage, mottled with black, tawny and white, and by 
their nocturnal or crepuscular habits. 
Key oF THE GENERA. 
A. Rictal bristles very long and conspicuous. 
a. Tarsus bare; nostrils tubular. Phalenoptilus, p. 243. 
b. Tarsus feathered; nostrils not tubular. Antrostomus, p. 243. 
B. Rictal bristles very small and hardly noticeable; tarsus half 
feathered. Chordeiles, p. 245. 
