414 ORNITHOLOGY. 



the West ITuniboldt Mountains it was very numerous in September. It 

 was found there in ever-restless companies, continually twittering as they 

 flew from bush to bush, at which time the flocks became greatly scattered, 

 the indi^-iduals straggling, or "stringing out," one behind another. In 

 all their movements they were remarkably restless, in this respect even 

 surpassing the Gnat catchers {Polioptilce), to which they bear considerable 

 i-esemblance in their movements and appearance. In November many of 

 these birds were seen in company with the Gray Titmice (Lopliophanes 

 inornatus) among the cedars on the Pea-vine and Virginia Mountains, and 

 adjacent ranges in western Nevada, and in the spring one or two flocks, 

 sup])osed to be this species, were observed in the gorge of the Carson Kiver, 

 near Carson City. On the eastern side of the Great Basin a few individuals 

 in City Creek Canon, near Salt Lake City, comprised all that were seen. 



Among the numerous specimens killed in September, we noticed that 

 many had the iris blackish, while in otlicis it was clear light sulphur- 

 yellow, and in some intermediate, or yellowish outwardly, and brownish 

 next the pupil. A close examination, however, of these specimens, showed 

 that this difference apparently depended on age, those having the darkest 

 eyes being unmistakably yovmg birds, while those in which the iris was 

 clear yellow were all old birds, as was readily detected by the difference 

 in the texture of their plumage. Even the youngest specimens had a 

 yellowish outer ring to the iris, concealed by the eyelids, so that it seems 

 that this color gradually .spreads from the outside to the pupil, with 

 advancing age, imtil, when fully mature, the iris becomes wholly clear 

 hght yellow. 



List of specimens. 



171, i juv.; West Humboldt Mountains, Nevada, September 7, 1867. 4| — 6—2 

 — IvJ — xji — i';. Bill, black; irix, sepia-black, very narrow outer yellowish ring ; tarsi 

 and toes, black. 



184, 9 ad.; West Humboldt -Mountains, September 11. 4J— 5|— 2— If^J— /^ 

 — 2| — Ijj. Bill, black; iris, light yellow ; tarsi and toes, black. 



18.-J, <J JHr.; Ai^—Q—2—{\]^\—f^—2^\—l. Iris, light yellow, brownish next 

 pupil. 



2.J0, at].; West Humboldt Mountains (east side), October 12, 1867. 4j\ — 6— 2J 

 — ]f — i — Ys — 2J — 'l§. Bill, tarsi, and toes, deep black; iris, sulphur-yellow. 



