Very small Formicariidæ (length about 120-135 mm.) with дong, slender bill (longer than head), long, slender tarsi (nearly as long as exposed culmen) and with tail four-fifths as long as wing.
Bill very long (longer than head), straight, and slender, its width at frontal antiæ decidedly greater than its depth at same point and equal to about one-fourth the distance from nostril to tip of maxilla; culmen sharply ridged, straight, the extreme end abruptly and rather strongly decurved, the tip of maxilla very minutely uncinate; maxillary tomium faintly concave for anterior half or more, very faintly (obsoletely) notched subterminally; mandibular tomium straight, faintly decurved terminally, without trace of subterminal notch, the tip of mandible very slightly decurved; gonys nearly straight, very slightly prominent basally. Nostril exposed, widely separated from feathering of latero-frontal antiæ, narrow, longitudinal, overhung by a broad, convex operculum. Rictal bristles distinct, but rather few and slender; feathers of chin without terminal setæ. Wing moderate or relatively rather large, with longest primaries extending slightly but decidedly beyond secondaries; fifth, sixth, and seventh primaries longest, the tenth (outermost) less than half as long as longest, the ninth much shorter than secondaries. Tail about four- fifths as long as wing, graduated (graduation less than distance from nostril to tip of maxilla), the rectrices (10) rather narrow, rounded terminally. Tarsus about as long as bill from frontal antiæ, two- fifths as long as wing, slender, the scutella of acrotarsium fairly distinct, those of the planta tarsi undivided; middle toe, with claw, about two-thirds as long as tarsus; outer toe, without claw, reaching to beyond middle of subterminal phalanx of middle toe, the inner toe decidedly shorter; hallux about as long as inner toe but much stouter; basal phalanx of middle toe wholly united to both outer and inner toes, the second phalanx partly united to outer toe; claws moderate in size and curvature, that of the hallux 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 brownish (back, etc., sometimes more grayish), the tail blackish, with or without whitish tip to rectrices; beneath whitish, more or less strongly buffy or rufescent laterally: sexes alike.
Range. — Guatemala to southeastern Brazil. (Four species.)
RAMPHOCÆNUS RUFIVENTRIS RUFIVENTRIS (Bonaparte).
NORTHERN LONG-BILLED ANTWREN.
Adults {sexes alike). — Pileum and hindneck plain olive-brown (between prouts brown and raw umber); rest of upper parts (except tail) plain deep grayish olive or olive-slaty, the concealed portion of
