Vol. VI] SWARTH— RACES OF BEWICK WREN 59 



mens might be thought of no especial significance. With a 

 series as extensive and representative as the one here assem- 

 bled, however, these variations can be recognized as parts of a 

 coordinated whole, and in the occasional instance where an in- 

 sufficient specimen or two from some obscure locality exhibits 

 an unexpected line of development, there is usually to be found 

 at least a possible explanation of the occurrence. 



The extent and manner of variation illustrated in this series 

 of birds can not be too strongly emphasized. For one thing 

 there are enough specimens at hand to show a surprising range 

 in characteristics from any one locality. Many stations are 

 represented each by numerous specimens of freshly molted 

 fall birds, undoubtedly individuals of the resident form of each 

 respective place, as they appear prior to any wear and tear 

 of the plumage. In every case there are individuals exhibit- 

 ing wide variation in appearance, though extremes may be 

 shown by but one or two specimens. These differences can 

 not be explained save as illustrating the amount of variation 

 to be encountered among individuals at any one point. 



These variants are not of the same nature as the "inter- 

 mediates" encountered near the line of meeting of two dif- 

 ferent races. In the latter case, as is well illustrated from many 

 such localities in the series here assembled, we find zvhole pop- 

 ulations showing characters variously intermediate between 

 two extremes. The occasional variants found elsewhere may 

 crop up at any place, and in appearance do not necessarily 

 incline towards any other subspecific type. It would almost 

 seem as though the species as a whole was in a formative 

 stage, showing occasional response to stimuli which we can- 

 not at present understand. 



In this connection it is well to consider conditions in the 

 Juvenal plumage. In the several distinguishable Pacific coast 

 forms of Thryomanes hezvicki the color differences shown in the 

 adults are accurately reflected in the juvenal plumage, young 

 birds of the different recognizable subspecies exhibiting vari- 

 ations of precisely the same nature as are seen in adults, usually 

 in about the same degree. This, according to the general 

 understanding of the significance of characters of the juvenal 

 plumage, would argue great age and consequent deep-seated- 

 ness of the color characters observed, which is hard to recon- 



