4 
44 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
Medium-sized (wing 138-160 mm.), stoutly built Charadrii with 
well-developed hallux, wedge-shaped bill, stout legs and feet, and 
scutellate acrotarsium and planta tarsi. 
Bill shorter than head, cuneate and acute in lateral profile, its 
depth at base equal to about one-third the length of culmen, the 
terminal portion narrow and flattened, the mesorhinium rather 
broad and flattened; sides of maxilla with a broad 1ateral groove, 
extending for less than half way from base to tip, the anterior end 
more or less rounded; base of mandible with a narrow lateral groove, 
extending for less then half the distance to tip; nostril sub-basal, 
longitudinal, linear, in lower edge of membraneous nasal fossa, 
Wing rather long, pointed, the longest primary (outermost) extending 
much beyond tip of longest tertials. Tail much more than one-third 
as long as wing, truncate. Tarsus decidedly longer than exposed 
culmen, about as long as middle toe with claw, the acrotarsium and 
planta tarsi each with a single row of transverse scutella, otherwise 
covered with small hexagonal scales; toes rather stout, the anterior 
ones fringed with a distinct, slightly scalloped, lateral membrane, 
the lateral ones much shorter than the middle one, the inner slightly 
shorter than the outer; interdigital spaces completely cleft; hallux 
well-developed, about as long as middle phalanx of middle toe; 
claws rather short, but stout and distinctly curved; lower portion of 
tibia unteathered. 
Coloration.—Under parts (except chest), upper rump, upper tail- 
coverts and greater wing-coverts, white; rest of plumage chiefly 
dusky, the upper parts sometimes varied with white and cinnamon- 
rufous, 
Range.—Sea coasts nearly throughout the world, but breeding 
only in northern portions of northern hemisphere. (T'wo species.) 
KEY TO THE SPECIES AND SUBSPECIES ARENARIA, 
a. Chin and throat white; summer adults with upper parts partly cinnamon-rufous. 
(Arenaria interpres.) 
b. Coloration darker; adult male in summer with blackish predominating on upper 
parts, and black streaks on pileum broader; adult female in summer with 
upper parts mostly, often almost wholly, grayish brown; wing averaging more 
than 150, tail more than 62 mm. (Greenland, northern Europe and Asia, 
and Alaska north of Aleutian chain; south in winter to Africa, Australia, 
Oceania, CtC:) svencuserecage esis cence cea Arenaria interpres interpres (p. 45). 
bb. Coloration lighter; adult male in summer with cinnamon-rufous and white 
predominating on upper parts, and black streaks on pileum narrower ; adult 
female in summer with cinnamon-rufous largely replacing grayish brown on 
upper parts; wing averaging less than 150, tail less than 61 mm. (North- 
eastern North America, from Mackenzie basin to Melville Island, etc.: in 
winter southward to southern Brazil, Chile, etc.) 
; Arenaria interpres morinella (p. 51). 
aa, Chin and throat deep sooty gray or dusky; summer adults without any cinnamon- 
rufous on upper, parts. (Pacific coast of North America and northeastern 
UD ONIA) 22 tio daciea Sumemarsteie latudaemermea a at. 2 Arenaria melanocephala (p. 55). 
