388 CLIMBING BIRDS— SCANSORES. 



P. Avicricanus, in all stages of color, is distiiiguislied from arctirus by the 

 white along the middle of the back, the absence of distinct frontal white 

 and black bands, more numei-ous spots of white on the head, etc. The inner 

 Avelis of inner secondaries are banded with white, not uniform black. The 

 maxillary black stripe is rather larger than the rictal white one, not 

 smaller ; the size is decidedly smaller. Females almost always have tlie top 

 of head spotted with white, instead of uniform black, wliich is the rule in 

 arcticus. Still, the relationship is very close ; and from the Xew Brunswick 

 specimens of P. Americumis, with ^'ery little white on the back, to typical 

 arcticus, \iii\\ovii any, is but a single step. In reality, if dorsalis and Avicri- 

 canus are one, Amcricanus and arcticus would scarcely seem entitled to 

 separation. 



It is possible that the difference in the amount of white on the iijiper 

 parts of tins species is to some extent due to age and season, the winter 

 specimens and the young showing it to the greatest degree. Still, however, 

 tliere is a decided geographical relationship, as already indicated. 



This species can be easily distinguished from the Picoicles tridactylus of 

 Northern and Alpine Europe, by the tail feathers ; of these, the outer three 

 are white (the rest black) as far as exposed, without any bands, the tip of 

 the third Iieing white only at the end. The supra-ocuhir white stripe is 

 very narrow and scarcely appreciable ; the crissum white and unhanded. 

 Tlie back is banded transversely in one variety, striped longitudinally in 

 the other. In P. tridacti/Ius, the two outer featliers on each side are white, 

 banded with black, the outer with the bands regular and equal from base ; 

 the second black, except one or two terminal bands. Tlie crissum is well 

 banded with black ; the back striped longitudinally with white ; the supra- 

 ocular white stripe almost as broad as the infra-ocular. P. crissolcucus, of 

 Siberia, is similar to the last, but differs in white crissum, and from both 

 species in the almost entire absence of dark bands on the sides. 



I follow Sundevall in using the specitic name Amcrimnus, Brehm, for this 

 species as being the tirst legitimately lielonging tii it. 1'. hirsutus, of 

 Vieillot, usually adopted, is liased on a Euro})ean bird, and agrees with it, 

 though referred by the author to the American. The name of undulcdus, 

 Vieillot, selected liy Cabanis, is based on Buflbn's figure (pi. enl. 5.53) of a 

 bird said to be from Cayenne, with four toes ; the wliole top of the head red 

 from Ixise of l)ill to end of occiput, with the edges of tlie dorsal featliers 

 narrowly white, and with the three lateral tail feathers regularly banded 

 with lilack, tipped with red ; the fourth 1 )anded white and lilack on outer 

 web, tipped with black. None of these features belong to the bird of Arc- 

 tic America, and the markings answer, if to any, better to the European. 

 (Baird.) 



