1920] Swarth: Revision of Avian Genus Passerella 179 



South of the Sierra Nevada the next breeding station of stephensi 

 is a limited area on the summit of Mount Pinos, some eighty miles 

 southwest of the southernmost station in the Sierras. Then, still 

 farther south, there are widely disconnected areas on the San Gabriel 

 Mountains, the San Bernardino Mountains, and the San Jaeinto 

 Mountains, separated from each other by many miles of lower zones. 

 In the San Jacinto Mountains points of occurrence are mostly from 

 8000 to 9000 feet, though a few birds were seen in one part of the 

 mountains as low as 6000 feet. In the San Bernardino Mountains the 

 subspecies occurs at about the same elevation, mostly from 7400 to 

 9000 feet ; in the San Gabriel Mountains it is known only from the 

 higher slopes of Mount Waterman from 7000 feet upward to the 

 summit (7752 feet altitude) ; and on Mount Pinos (altitude 8826 feet) 

 from 8000 feet upward. In the Sierra Nevada the vertical range is 

 from 7000 to 10,000 feet. 



It is a notable fact that, despite the isolation of these several 

 colonies and the demonstrated plasticity of the species throughout 

 its range, there are no discernible differences between specimens of 

 stephensi from the several regions occupied. Considering the varia- 

 tion existing between the many closely connected subspecies, and the 

 way in which each represents a step from one extreme to another, it 

 might be expected that such widely parted groups as those into which 

 stephensi is divided would illustrate separate and distinguishable 

 stages as they advanced farther and farther from the starting point, 

 but such is not the case. In the series at hand I am unable to appre- 

 ciate any tangible features serving to distinguish birds even from the 

 extremes of the subspecies' range. The most that can be said regard- 

 ing such differences is that in the series from Hume, Fresno County 

 (the northernmost point at which stephensi has been collected), there 

 are certain small-billed individuals that may be taken to illustrate 

 intergradation with the nearby form mariposae, but in the same series 

 there are other specimens with quite as large bills as the maximum 

 from any other place. In other words, while stephensi is the culmin- 

 ation of a series of steps from canescens and through monoensis and 

 mariposae, the maximum of change is reached as soon as the habitat 

 of the subspecies is entered at the north, where mariposae and stephensi 

 come together. There is no further accentuation of character in the 

 extensive but disconnected habitat of stephensi as it extends southward. 



Stephens fox sparrow is a summer visitant onl}^ upon its breeding 

 grounds, but there are neither specimens nor notes available indicating 



