CYPSELID-E — TFIK SWIFTS. 427 



hundred i'cet liij,di. It soemod to be very wary, and Hew witli j^reat velocity, 

 rarely descending within reacli of the guns. 



The White-tiiroated Swift was met witii in great abundance by Mr. Ividg- 

 way at the East Humboldt Mountains, and was seen by him more sparingly 

 in the Toyabe and Wahsatch. In the former mountains it inhabited the high 

 limestone cliHs which walled the caftons, congregating in thousands, and 

 nesting in the chinks or crevices of the rocks, in company with the Violet- 

 green Swallow {Tac/i//riiirf(i (ludiissimt). It was a very noi.sy species, having 

 a vigorous chatter, reminding one somewhat of the notes of young IJaltimore 

 Orioles when being fed by their parents. It was also very |)Ugnacious, a 

 couple now and then being seen to fasten upon one anotlier higii up in the 

 air, and, clinging together, falling, whirling round and round in their descent, 

 nearly to tlie ground, when they would let go each other, and separate. 

 A couple would often rush by with almost inconceivable velocity, one in 

 chase of the other. Their flight was usually very high, or, if tiiey occasion- 

 ally descended, it was so swiftly that Mr. Kidgway only succeeded in shoot- 

 ing tln'ee specimens, while he found it utterly impossible to reach their nests, 

 which were in the horizontal fissures in the face of the overhanging cliff. 



Subfamily CHJETURINJE. 



This subfamily is characterized by having tlie normal number of plialanges 

 to tlie middle and outer toes (4 and 5, instead of 3 and 3), tlie backward 

 position of the hind toe, and the naked tarsi, which do not (iven appear to 

 be scutellato, but covered with a soft skin. Of the two North Americati 

 genera, O/mfirra has spinous projections at the end of the tail-feather.'^, 

 while in Xepkn'cctcs the sliafts of tlie tail-feathers, though stilfened, do not 

 jiroject beyond the plume. 



■ This .subfamily appears to 'be composeil of two definable sections, with 

 subdivisions as follows : — 



A. Tail forked; si>inoii.< points of the feathers not cxtendin;,' far lieyond the 

 webs, or entirelj' wanting. Feathering of the .siile.s of the forehead (extending 

 forward outside the nostrils nearly to their anterior end. 



fi. No trace of .siiinou.s jioints to tail-feathers. Feathering of frontal points 

 almost oonii)let,ely enclosing the nostiils lietween them. No lif^Jjl collar 

 round the neck; sides of the foreheail with a hoary suirnsiou . . Nephccceies. 

 , b. Spinous points of tail-feathers distinct. A light collar round the neck. 



1. Nostril ii» hi Xe.jihu'fefei>. Siiles of forehead with a hoary sull'usion. 

 Collar chestnut. Wing less than r)..")0. (('. riitiht.) 



2. Feathered frontal j)oints narrower, not reaching anterior end of 

 nostril. Sides of forehead without hoary suffusion Collar white. 



Wing more than 8.00 Ilemiprocne. 



Ba Tail rounded ; spinous points of the feathers much elongated and j)rojectiMg. 

 Feathering of sides of forehead scarcely reaching beyond posterior end of nostril. 

 Wing less than 5.50 Cliaiiirti, 



