BIRDS OF NORTH AND MIDDLE AMERICA. 25 



Limicolse with supraorbital grooves and occipital foramina pres- 

 ent; coracoids separated; hallux (if present) small and elevated, 

 often absent; anterior toes and claws of moderate length or rela- 

 tively short, and rectices, 12 or more. 



KEY TO THE FAMILIES OP CHARADHII. 



a. Bill either much shorter than head or relatively stout (never subulate), more or 



less compressed, usually more or less swollen distally anterior to the more or less 



constricted middle or subbasal portion, or if not thus swollen and constricted 



the bill subcuneate in lateral profile (Arenariidse); nasal fossae rounded and 



relatively broad at anterior end. 



b. Bill much longer than tarsus, excessively compressed distally, much deeper 



than ^vide throughout, deepest in middle or posterior to the middle portion, 



the upper and lower outlines converging subbasally; tip of both maxilla 



and mandible broad (rounded or subtruncate) in lateral profile; gonys more 



than t\vice as long as mandibular rami. (Thigh-muscle formula ABXY.) 



Heematopodidse (p. 26). 



66. Bill shorter than tarsus, not distinctly (if at all) compressed distally, not much 



deeper than wide, deepest either anterior to middle portion or (in Arenariidae) 



at extreme base, the upper and lower outlines converging for basal half or 



more or (in Arenariidae) not at all converging; gonys not twice as long as 



mandibular rami. 



c. Hallux well developed (as long as basal phalanx of outer toe); acrotarsium 



distinctly and regularly transversely scutellate. 



d. Bill subcuneate in lateral profile (not swollen terminally nor contracted in 



middle portion); planta tarsi transversely scutellate; toes more slender, 



without distinct lateral pads; tail slightly rounded. (Thigh-muscle 



formula AXY.) ■ Arenariidee (p. 42) 



dd. Bill plover-like (swollen terminally, contracted in middle portion); planta 

 tarsi reticulate (covered with small roundish or hexagonal scales); toes 

 stouter, with conspicuous tumid lateral pads; tail emarginate. (Thigh- 

 muscle formula ?) Aplirizidee (p. 57). 



cc. Hallux usually absent, if present very small (much shorter than basal phalanx 

 of outer toe), acrotarsium not regularly transversely scutellate, usually 

 reticulate, or covered with, rather small hexagonal scales. (Thigh-muscle 



formula ABXY.) Charadriidse (p. 61), 



aa. Bill variable as to length but not swollen distally, not contracted in middle or 



subbasally, not cuneate in lateral profile; nasal fossae narrow and pointed at 



anterior end. 



6. Tarsus less than twice as long as middle toe with claw, the acrotarsium (usually 



• planta tarsi also) a regularly transversely scutellate; naked portion of tibia 



shorter than middle toe with claw (whole of tibia sometimes feathered). 

 c. Toes without a distinct lateral membrane; tarsus not unusually compressed; 



plumage of iinder parts not dense (gull-like) Scolopacidae (p. 143). 



cc. Toes with a conspicuous lateral membrane, sometimes developed into broad 

 scalloped lobes; tarsus excessively compressed; plumage of under parts 



very dense, gull-like Phalaropodidae (p. 416). 



66. Tarsus more than twice as long as middle toe with claw, wholly reticulate 

 (covered all round with small hexagonal scales); bare portion of tibia much 

 longer than middle toe with claw. (Plumage of under parts as in Phalar- 

 opodidae) Recurvirostridae (p. 435) 



o The only exceptions to the transversely scutellate planta tarsi are the genera 

 Numenius, Phaeopus and Mesoscolopax (part.) 



