NO. 2265. THE WREN GENUS NANNUS BILLBERQ—OBERHOLSER. 



233 



Measurements. — Male:^ wing, 50-53 (average, 51.6) mm.; tail, 

 30-36 (32.9) ; exposed culmen, 12.5-15 (13.8) ; tarsus, 17.5-20 (18.6) : 

 middle toe without claw, 12.5-14.5 (13.7). 



Female:- wing, 47-50 (average, 49.2) mm.; tail, 30-33 (31.5); 

 exposed culmen, 12.5-13.5 (13) ; tarsus, 18-19 (18.3) ; middle toe 

 without claw, 13-13.5 (13.3). 



Type-locality. — IJnalaska Island, Aleutian Islands, Alaska. 



Geographic distribution. — Unalaska, Amaknak, and Akutan Is- 

 lands in the Aleutian Islands, Alaska. 



Remarks. — This new race may be readily distinguished from 

 Nannus troglodytes alascensis, with which it has heretofore been con- 

 sidered identical, owing, of course, to tlie imperfect material avail- 

 able from the Pribilof Islands, the type-locality of the latter. The 

 good series now at hand makes evident its excellent characters of 

 both in size and color. It is, in fact, nearest to Nannus troglodytes 

 tanagensis, from which it differs in its decidedly shorter bill; some- 

 what more abbreviated wing; more rufescent upper parts; and more 

 deeply ochraceous lower surface. It is apparently confined to the 

 islands of Unalaska, Amaknak, and Akutan. 



Detailed measurements of adult specimens are as follows : 



Measurements of specimens of Nannus troglodytes petrophihis. 



1 Ten specimens, from Unalaska, Amaknak, and Akutan Islands, Aleutian Islands, 

 Alaska. 



2 Three specimens, from Unalaska Island, Alaska. 

 ' U.sed In measurement averages on p. 238. 



■* Type. 



