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 smaU 

 and weak. 



Key of the Families. 



A. Bill short, broad and depressed, but gape very large. 



a. Plumage lax and soft ; claw of middle toe pectinated. 



Caprimulgidae, p. 242. 



b. Plumage firm and hard ; claw of middle toe not pectinated. 



Cypselidae, p. 248. 



B. Bill very long and slender, gape not deeply cleft ; plumage 



more or less metallic. Trochilidae, p. 251. 



Family CAPRIMULGIDAE. 



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. Phalsenoptilus, 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. 



