APPENDIX C. — BIEDS. 815 



evident from the table of comparative measurements. The bill, 

 too, of the latter, although of much the same proportions, is de- 

 cidedly smaller. 



As in S. arctica, the upper parts are a bright azure blue, more 

 lustrous and deeper on the wings, rump, and tail-coverts. The 

 lower parts are of a light greenish blue, excepting the lower belly 

 and sides, abdomen, and tail-coverts, which are white. 



The white of the lower parts is clearer and extends higher up 

 on the belly than in S. arctica, and the quills and tail-feathers 

 are much bluer, this colour greatly predominating over the brown 

 on the inner webs and inner faces of the feathers. The clove- 

 brown shows somewhat conspicuously as a broad tip to the quills, 

 which, besides, are very narrowly margined, terminally and inter- 

 nally, with whitish. The outer margins of the primaries, towards 

 the tips, shade into greenish blue. Owing, perhaps, to the plum- 

 age not being quite full, many of the feathers of the back and 

 breast have grayish tips. 



DIMENSIONS. 



Sialia macroptera, (Salt Lake, Male.) S, arctica, (Fort Union, Male.) ^ 



Total length 7 i inches. (Skin contracted) 6J inches. 



Extent 14:j% " " 



Wing folded 4J-| " '« 4f| " 



Tail to insertion of middle feathers 3y*j " " 2f " 



Depth of fork f| " (Tail worn) f| " 



Projection of longest primary be- 

 yond longest secondary or ter- 

 tiary, (wing not shut close) l-Jy^j^ " 



Do. wing shut close If lj\ " 



Longest primary beyond shortest, 



(9th)..... lif " 1/j « 



Second primary longer than first, 



(spurious) 3|| " 2ff " 



Bill along ridge f| " ff " 



Bill, gape f| " |f " 



Tarsus jf " \op « 



Middle toe j\ " , f| « 



" " with claw jf " i^p " 



Lateral toes, (equal) ff " ^^ " 



with claw j\ " j'j 



Hind toe ^^ " A^ " 



" " with claw j% " ^ " 



(In S. macroptera.) 

 1st quill spurious ; 3d, longest ; 2d, little shorter ; 4th, rather less than 2d, 



