Page:Birds of North and Middle America partV Ridgway.djvu/116

88 Genus MICROBATES Sclater and Salvin.

Very small, long-billed, long-legged Formicariidæ, similar in appearance to Rhamphocænus but with shorter and broader bill, longer tarsi, relatively longer toes (especially the hallux), narrower nostrils with differently shaped operculum, and much shorter tail (only about half, instead of four-fifths) as long as wing.

Bill about as long as head, nearly straight, its width at latero- frontal antiæ much greater than its depth at same point and equal to much more than one-third the distance from nostril to tip of maxilla; culmen sharply ridged, straight for basal half (more or less), then very gradually decurved until near end, where more strongly decurved, the tip of maxilla minutely but distinctly uncinate; maxillary tomium faintly concave, minutely notched subterminally; mandibular tomium very faintly convex, at least terminally, without trace of subterminal notch; gonys faintly convex basally, straight terminally. Nostril exposed, distinctly separated from feathering of latero-frontal antiæ, narrow, longitudinal (slit-like), overhung by a broad but not convex membraneous operculum. Rictal bristles distinct but rather few and slender; feathers of chin without terminal setæ. Wing rather large, with longest primaries extending slightly beyond secondaries, much rounded; fifth and sixth primaries longest, the tenth (outermost) less than half as long as the longest, the ninth very much shorter than, the eighth about equal to, secondaries. Tail slightly more than half as long as wing, rounded (graduation equal to much less than half the distance from nostril to tip of maxilla), the rectrices (10) rounded at tip. Tarsus very long (decidedly longer than whole culmen, nearly half as long as wing), slender, the acrotarsium faintly scutellate, the planta tarsi completely fused; middle toe, with claw, decidedly shorter than tarsus (equal to or slightly longer than exposed culmen); outer toe, with claw, reaching to about middle of subterminal phalanx of middle toe, the inner toe decidedly shorter; hallux much longer than inner toe (about as long as outer toe), much stouter; basal phalanx of middle toe wholly united to both lateral toes; claws moderate in size and curvature, that of the hallux much shorter than its digit. Plumage full, soft, and blended, that of rump and flanks elongated, more lax or fluffy; feathers of pileum not elongated.

Coloration. — Above plain brown; sides of head blackish and white, or tawny; beneath white passing into dusky on flanks and under tail- coverts, the chest crossed by a band of black (M. collaris) or under parts of body gray, chest streaked with black and white, and throat white bordered on each side by a black stripe; sexes alike. 