ORNITHOLOGICAL EXPLORATIONS. 



177 



From the American form, the occurrence of which on the mainland of 

 Alaska along the Bering Sea has not yet been reported,* it differs not 

 only in lacking the black stripe dividing the white wing-speculum, 

 but the border line of the feathering on the bill is so differently ar- 

 ranged in the two forms, and so constant, that the appellation of Mer- 

 ganser merganser americanus is not defensible. 



In order to make these differences better understood, I tabulate them 

 as follows : 



Merganser americanus. 



Merganser merganser. 



(1) The distance from the loral ajiex (1) The distance from the loral apex to 



to the angle of mouth is equal to half the angle of mouth is equal to or longer 



the distaurie from the loral apex to the than the M)/toZe distance from the loral apex 



posterior corner of the nostrils; to the posterior corner of the nostrils; 



(2) The distance from the loral apex to 

 the imsierior corner of the nostrils is 



(a) al)out equal to half the distance from 

 the anterior corner Of the nostrils to the 

 til) of the bill, 



(6) and considerably longer than the dis- 

 tance from the loral apex to the tip of 

 the naked frontal angle; 



(3) The distance from the frontal apex 

 to the posterior corner of the nostrils 

 is sliorter than the distance from the loral 

 apex to the same point. 



(4) Wing-speculum white, divided by 

 a transverse black bar. 



(2) The distance from the loral apex to 

 the posterior corner of the nostrils is 



(a) about equal to one-third the distance 

 from the anterior corner of the nostrils to 

 the tip of the bill, 



(6) and shorteror equal to the distance 

 from the loral apex to the tip of the 

 naked frontal angle ; 



(3) The distance from the frontal apex 

 to the posterior corner of the nostrils is 

 equal to the distance from the loral apex 

 to the same point. 



(4) Wing-speculum white, undivided. 



This species is rather common in Kamtschatka, but being more an 

 inland bird than M. serrator it occurs on Bering Island in limited num-. 

 bers only. 



In 1883 the first new-comers — the species does not winter on the 

 islands — were observed on April 15. 



A male ( U. S. Nat. Mus. M. 92872 ; L. Stejneger No. 2027) shot on 

 Bering Island, May 17, 1883, measures as follows : Total length (654)"'^". 

 Wing, 297™™ ; tail-feathers, 110™™; culmen, 55™™ ; tarsus, 52™™. Middle 

 toe with claw. 



* It has been obtained at Alexandrovsk, Kenay (Finsch) ; Ft. Yukon, Sitka, Una- 

 laschka (Dall); Kodiak (Beau) ; Chilcoot (Hartlaub). 



15861 Bull. 29 12 



