BIRDS OF NORTH AND MIDDLE AMBEICA. 537 



c. Slightly paler; wing averaging 167.9 in male, 162.7 in female; tail averaging 



156.7 in male, 141.8 in female. (Eastern Tabasco, Campeche, Yucatan, and 



northern British Honduras.).. Nyctidromus albicollis yucataneusis (p. 543). 



cc. Slightly darker; wing averaging 171 in male, 162.1 in female; tail averaging 



163.7 in male, 144.5, in female. (Vera Cruz to Tabasco.) 



Nyotidromus albicoUis sumichiasti (p. 543). 



66. Wing averagii^ 173 or more in males, more than 168 in females; taU averaging 



more than 164 in males, more than 150 in females. 



c. Wing averaging 173 in male, 170.1 in female; tail averaging 164.9 in male, 



154.9 in female; coloration browner. (Tres Marias Islands, western Mexico.) 



Nyotidromus alblcoUis insularis (p. 545). 



ce. Wing averaging 182.1 in male, 170.1 in female; tail averaging 176.6 in male, 



150.4 in female; coloration grayer. (Extreme northeastern Mexico and 



southern Texas.) Nyotidromus albicollis merrilli (p. 546) 



NYCTIDROMUS ALBICOLLIS ALBICOLLIS (Gmelin). 



cddSto.o 



Gray-hrown phase. 



Adult male. — Pileum, hindneck, and interscapular region grayish 

 brown, minutely vermiculated with dusky, the median portion 

 streaked with black, the streaks much larger and broader along 

 median line of crown and occiput; inner webs of some scapulars 

 brown or grayish brown, minutely vermiculated with dusky, of others 

 black edged with brown,the outer webs mostly black edged (more 

 or less broadly) with buflf, this buflF edging passing round tip. of some 

 feathers; rump and upper taH-coverts brown or grayish brown, 

 vermiculated with dusky, and with mesial ragged streaks of black; 

 middle pair of rectrices grayish brown, coarsely vermiculated, 

 marbled, or splashed with dusky with larger cloudings or marblings 

 of dull black, these with a tendency toward forming indications of 

 irregular transverse bands; the next pair similar but with the darker 

 markings larger; third and fourth pairs white with basal portion 

 broadly barred with black and buff (or with greater part white) and 

 with more or less of dull black or dusky on distal portion of outer 

 webs, this sometimes nearly absent on third pair, but usually present 

 as a broad edging for terminal fourth (more or less), but on fourth 

 pair occupying fuU width of outer web for terminal third or more, and 

 continued proximally along edge, sometimes quite to base of the 

 white area; the fifth (outermost) pair mostly brownish black, some- 

 times wholly so except for a slight mottling of buff along edge of 

 basal portion of inner web;'' prevalent color of wing-coverts brownish 



"■ The Central American vernacular name; pronounced coo-ySf-ho, in imitation of 

 the call or song. 



6 The relative proportion of the white and colored areas on the three lateral pairs 

 3f rectrices is so variable (possibly according to age) that it is very difficult to give a 

 lescription that will cover all cases. From a careful examination of abundant material 

 [ am satisfied, however, that this variation affects equally all forms of the species. 



