Males call from shallow water. All breeding congregations of this species that we have found were in a grassy marsh, 7.5 kilometers west of Puerto Viejo, Costa Rica. Tadpoles were found in water-filled depressions in the marsh at night. When first observed, tadpoles were near the surface of the water; they responded to light by quickly taking refuge in the dense grass. No tadpoles were observed by day. The breeding call consists of a low squawk, usually followed by a series of one or more rattling secondary notes (duration of primary notes, 0.06-0.35 seconds; of secondary notes, 0.10 to 0.47 seconds), repeated at intervals of 5 to 55 seconds. The primary notes have 187 to 240 pulses per second and major frequencies of about 740 to 1870 cycles per second (Pl. 11A). Only six tadpoles are available for study. Four of them in stage 34 of development have body lengths of 9.0 to 9.5 mm., tail lengths of 14.0 to 15.0 mm., and total lengths of 23.0 to 24.5 mm. One tadpole in stage 38 and one in stage 40 have total lengths of 31.0 mm. A typical tadpole in stage 34 of development (KU 91807 from 7.5 km. W Puerto Viejo, Heredia Province, Costa Rica) has a body length of 9.5 mm., tail length of 15.0 mm., and total length of 24.5 mm.; body about three-fourths as deep as wide; snout rounded dorsally and laterally; eyes widely separated, directed dorsolaterally; nostril about midway between eye and tip of snout; mouth anteroventral; spiracle sinistral, about two-thirds distance from snout to posterior end of body and slightly below midline; anal tube dextral; caudal musculature slender, barely curved upward distally; dorsal fin extending onto body; at mid-length of tail, depth of caudal musculature equal to that of dorsal fin and ventral fin; body grayish brown, palest ventrally; caudal musculature pale creamy yellow with bold gray reticulations; caudal fins transparent with gray reticulations anteriorly and black flecks posteriorly on both fins (Fig. 14A). Median part of upper lip bare; rest of mouth bordered by two rows of short blunt papillae; lateral fold present; tooth-rows 2/3; upper rows equal in length; second upper row broadly interrupted medially; three lower rows complete, first and second rows equal in length, slightly shorter than upper rows; third lower row noticeably shorter; upper beak shallow, forming broad, continuous arch with slender lateral processes; lower beak slender, broadly V-shaped, both beaks finely serrate (Fig. 15B).