1920] Swarth: Revision of Avian Genus Passerella 137 



selves a much wider range of variation than is seen in the series from 

 the summer habitat, showing practically every degree of divergence 

 from typical sinuosa, on the one hand toward unalaschcensis, on the 

 other toward annectens. These different types of birds, it is to be 

 inferred, hail from appropriately intermediate localities between the 

 summer home of typical sinuosa and the homes of the races they 

 apparently approach in appearance. Whether the whole Passerella 

 population from any one such place is uniformly of intermediate 

 appearance, or whether in such regions a percentage of intermediates 

 occurs among a preponderantly typical population, are questions 

 which can not now be answered. The field work carried on at such 

 points has as yet been insufficient to solve these problems. Among 

 winter birds there are other non-typical specimens also, apparently 

 referable to sinuosa, but showing a trend of variation not to be 

 explained as an approach either to unalaschcensis or to annectens. 



There are four birds from Vancouver Island (nos. 1623, 4082, 

 4091, 4095, Victoria Mem. Mus.) that I have provisionally placed with 

 sinuosa though they are certainly not typical examples of that sub- 

 species. One of these (1623) taken at Victoria on April 29, and 

 probably a north-bound migrant, is, perhaps, to be explained as an 

 intermediate toward annectens; but the other three, winter birds from 

 Departure Bay, present peculiarities of dark coloration and thick bill 

 not to be explained as an approach toward any other neighboring race. 

 It is always possible in such a case that while the superficial appear- 

 ance of the specimen is most nearly like some one race (in this case 

 sinuosa), its real affinities lie elsewhere ; and that its peculiar characters 

 may be due to an intermediateness of distribution in summer at present 

 not understood. There are such large expanses of territory in the 

 Pacific northwest where fox sparrows must occur and where no 

 collecting has been done, and the manner of variation throughout the 

 group is as yet so imperfectly known, that it is too much to be expected 

 that the peculiarities of all winter specimens collected be perfectly 

 understood. 



Aside from these aberrant specimens there is no example of sinuosa 

 at hand from any point between Prince William Sound and northern 

 Oregon, though extensive collecting has been carried on at many places 

 in this region. The inference to be drawn is that travel between 

 summer and winter homes is for the greater part of the distance by 

 one continuous flight with few or no stops. 



