BIKa>S — TUKDIDAE — SIALIA AKCTICA. 



225 



separating the featliers. The quills are much edged with paler. The young birds have this 

 brown streaked with white, except on the crown ; indeed, the under parts may be described 

 sometimes as whitish, with narrow brownish edgings to the feathers on the under parts 

 anteriorly. 



The bill of this species is much stouter than in mexicana, as well as longer than in sialis. 

 The wings also are longer in proportion, reaching nearly to the end of the tail, which is more 

 deeply forked than in either of the others. The male birds of the three species are readily dis- 

 tinguishable ; the females are all much alike. The greener blue, the absence of rufous brown on 

 either back or belly, and the longer wings, will serve to separate the latter. 



In the zoology of Stansbary's report 1 characterize a species under the name of /S'l'aKa macrop- 

 tera on the ground of the unusually long wings, the weak claws, and the different shade of 

 blue. This specimen (370G, Salt Lake, March 21, 1851) still remains quite unique in these 

 respects. I am, however, now inclined to consider it as only a larger race, because more 

 northern, of the S. arctica, strengthening the general proposition of the greater size of resident 

 winter or summer specimens in northern than southern localities. The weak claws may have 

 been an individual peculiarity. All the specimens before me, nearly thirty in number, agree, 

 with scarcely an exception, in the smaller size and shorter wings. 



List of specimens. 



29 b 



