208 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Yol.YI. 



if an area of vegetation, composed of a certain class, be fouad, we geo.- 

 erally know what may be expected as typical of. that area. The greater 

 altitudes attained in the Eocky Mountains have furnished additional 

 facts regarding the breeding of certain species which may truly be con- 

 sidered sub-alpine when compared with their northward range. Future 

 investigations will throw mtich light upon this subject, especially so in 

 connection with the region under consideration. 



LIST OF BIRDS. 



TUEDID^. 



Hylociclila ustulata (l^utt.) Baird. — Eusset-backed Thrush. 



Appears to be a rare visitor in Nevada, Mr. Eidgway having obtained 

 but a single specimen not far from the eastern base of the Sierras, in 

 the Truckee Valley. It occurs more frequently, according to this ob- 

 server, in the pine-elad regions of the mountains. 



Hylocichla ustulata swainsoni (Caban.) Eidgw. — Olive-backed Thrush. 



Was found by Mr. Eidgway in the eastern portion of the State at the 

 East Humboldt Mountains. IJfo specimens were noted in the interior of 

 Nevada. 



Hylocichla imalascce (Gmel.) Eidgw. — Dwarf Thrush. 



Of rare occurrence. Mr. Eidgway secured but one specimen at Trout 

 Creek, Upper Humboldt Valley, and Dr. Cooper saw but a few in the 

 Colorado Valley, where they seem to remain only for the winter, and none 

 after April 1. 



Merula migratoria propinqua Eidgw. — Western Eobiu. 



Usually found in abundance along the timbered bottom lands of the 

 upper portion of the State. During breeding season occur in the tim- 

 bered mountains, as at Bull Eun, where these birds were building dur- 

 ing the latter part of May, although the snow had not all disappeared in 

 the ravines about the foot-hills. Mr. Eidgway found this species ex- 

 tremely abundant in the vicinity of Carson City from the middle of 

 March until the middle of April, and again in the valley of the Truckee, 

 below the " Big Bend," in August, being attracted thither by the fruit 

 of the buffalo-berry {SJiepherdia argentea). According to Dr. Cooper but 

 few came about Fort Mojave during the winter, though flocks are said 

 to wander as far south as Fort Yuma. 



The Eobin is said to be a winter resident, selecting the underbrush, 

 willows, and cotton woods fringing the streams. The only difference be- 

 tween this and the eastern species is the general pallor of the plumage, 

 for which it has been distinguished as a geographical race, and for which 

 Mr. Eidgway at first proposed the name Turdus migratorius propinquus, 

 Eidg.* 



*BuU. NuttaU Omith. Club, v. ii, 1877, p. 9. 



