PLECTROPHENAX. 403 
b. Larger, with much larger and longer bill. Male: Wing 4.25-4.70 (4.45), 
tail 2.85-3.20 (2.99), culmen .47-.52 (.50), gonys .26-.29 (.28). Female: 
Wing 4.10-4.25 (4.20), tail 2.75-2.80 (2.77), culmen .48-.50 (.49), gonys 
24-27 (.26). Eggs .93 x .69. Hab. Prybilof Islands, Alaska, and Com- 
mander Islands, Kamtschatka. 
534a, P. nivalis townsendi Ripaw. Prybilof Snowflake,' 
a, Male with black on only two middle tail-feathers, and on these restricted to a 
subterminal spot (sometimes almost obsolete); female with only four mid- 
dle tail-feathers chiefly blackish. Adult male in summer: Pure white, in- 
cluding entire back; a blackish spot on inner web of first tertial (sometimes 
second also) ; terminal portion (less than exposed half) of longer quills black, 
this reduced on fifth quill (and, if present, on sixth also) to a small spot near 
tip of inner web, the outer webs of all edged and margined terminally with 
white; two middle tail-feathers marked near end of inner webs with a small 
black spot; bill entirely black. Jn winter, similar, but top and sides of head 
washed with deep rusty, the hind-neck, back, ramp, and band across chest 
more faintly tinged with same; bill yellow, tipped with dusky. Adult female 
in summer: Pure white, the back and scapulars narrowly streaked with 
blackish (streaks broader and more wedge-shaped on scapulars), tertials with 
most of concealed portion blackish, the outer webs partly buffy brown, outer 
webs of second to fourth, fifth, or sixth quill dusky quite to the base, but 
broadly edged with white, all of them broadly margined at tips with the 
same; alule dusky bordered with white, and primary coverts sometimes 
dusky medially, but often entirely white; four middle tail-feathers blackish 
or dusky, broadly margined (both webs) with white, this involving nearly 
whole of outer web of next to middle pair; bill dusky. Jn winter similar, 
but upper parts, especially top of head and ear-coverts, washed with rusty, 
and bill yellow, tipped with dusky. Young: Top of head, hind-neck, back, 
scapulars, rump, and lower tail-coverts brownish gray (rather paler than 
in P. nivalis), the scapulars and interscapulars dusky centrally, forming broad 
but indistinct streaks; tertials with tips of both webs and broad edging to 
outer web umber-brown, the rest black; wings otherwise chiefly white, but 
marked with dusky, as in adults; lower parts dull white, purer posteriorly, 
tinged with pale smoky gray anteriorly; bill lemon-yellow. Male: Length 
about 7.00-7.50, wing 4.60-4.65 (4.62), tail 3.10-3.15 (3.12), culmen .44, gonys 
.24-.25. Female: Length about 6.50-7.00, wing 4.20-4.30 (4.25), tail 2.70- 
2.90 (2.83), culmen .42-.43, gonys .23. Hab. Breeding on Hall Island (prob- 
ably also St. Matthew’s Island), Bering’s Sea, and in winter visiting western 
coast of Alaska (St. Michael’s to Nushagak). 
535. P. hyperboreus Ripcw. McKay's Snowflake, 
1 New subspecies. Type, No. 106,695, Otter Island, Bering’s Sea, June 8, 1885; C. I. Townsend. 
