l40 Bent, Variation in Black-throated Loons. LApril 



in a point and the reflections of the throat are usually more green- 

 ish than in the others. I have yet to see a specimen in which more 

 or less purple reflections could not be found. Even Dr. Dwight's 

 type shows " slight purplish tints." This form, if it is a good sub- 

 species, has no well defined habitat; but what specimens I have 

 seen would seem to indicate a breeding range on both sides of 

 Bering Sea. which may extend for a considerable distance westward 

 into the interior of Siberia. 



The above arrangement may appear satisfactory to the casual 

 observer, but the trouble with it is that all of the above characters, 

 particularly those on which Dr. Dwight bases his new species, are 

 decidedly variable and inconstant. Size is the most satisfactory 

 character but even this shows intergradation or overlapping and 

 greater individual variation in each group than the differences in 

 averages between the groups. The measurements, in inches, of the 

 four forms, which I have taken or had sent to me, are as follows: — 



Gavia arctica pacifica {Lawrence). 



12 males from North America, east of the Mackenzie River, 



average, bill 2.1-4 wing 11.65 

 largest, " 2.32 " 12.42 

 smallest, " 1.93 " 10.80 



13 males from North America, west of the Mackenzie River, 



average, bill 2.06 wing 11.66 

 largest, " 2.20 " 12.50 

 smallest, " 1.S7 " 10.50 



Gavia arctica suschlcini (Sarudny) 



5 males from Turkestan, 



average, bill 2.35 wing 12.40 

 largest, " 2.60 " 13.35 

 smallest, rt 2.20 " 11. SO 



Gar-ia arctica arctica (Linnaeus) 



6 males from Europe, 



average, bill 2.44 wing 12.24 

 largest, " 2.62 " 12.75 

 smallest, " 2.30 " 12. 



