_Diagnosis._--Dark brown lateral stripe, if present, usually extending only to insertion of forearm, never posteriorly to sacral region; white line above brown stripe absent or faint; dorsal pattern weak, usually consisting of irregular dashes or interconnected lines; interorbital dark mark present; shanks having weakly defined transverse bars. _Description and variation._--In the majority of specimens (70%) the lateral dark stripe extends from the nostril to the eye and thence above the tympanum to a point above the insertion of the arm; in 17 per cent the stripe extends to the mid-flank, whereas in 13 per cent the stripe is absent. A narrow and faint white line is present on the canthus in some specimens, but no distinct white stripe is present above the lateral dark line posterior to the eye. An interorbital bar and transverse marks on the shanks are invariably present. The dorsal markings are variable, but in most specimens (92%) consist of either an X- or )(-shaped mark in the scapular region; in the other specimens the markings are irregular short lines or absent. Approximately equal numbers of specimens have a transverse bar, chevron, or broken lines in the sacral region, whereas about eight per cent of the specimens lack markings in the sacral region. When active at night, individuals are pale yellowish tan with faint brown dorsal markings. By day they are tan with more distinct brown markings (Pl. 14). The thighs are pale yellow; the belly is white. The iris is pale creamy tan with brown flecks. In breeding males the vocal sac is yellow. _Tadpoles._--Tadpoles of this species have been found in an extensive grassy pond at Puerto Viejo, Costa Rica. The following description is based on KU 104099, a specimen in development stage 36 (Gosner, 1960). Total length, 21.0 mm.; body length, 6.7 mm.; body slightly wider than deep, snout pointed; nostrils large, directed anteriorly, situated near end of snout; eyes small, situated dorsolaterally, directed laterally; spiracle sinistral, located just posteroventral to eye; anal tube dextral. Tail xiphicercal; caudal musculature moderately deep, extending far beyond posterior edge of fins; fins deepest at about midlength; dorsal fin extending onto body, slightly deeper than caudal musculature; ventral fin slightly shallower than musculature. Mouth small, terminal, lacking teeth and fringing papillae, but having finely serrate beaks. In preservative top of head olive-tan with brown flecks; dark stripe from snout through eye to posterior edge of body; belly white, flecked with brown anteriorly; tail creamy tan with grayish brown blotches. In life, dorsum of body reddish tan mottled with darker brown; lateral stripe dark brown; belly white, mottled with brown and black; caudal musculature heavily pigmented with grayish tan; posterior tip of tail marked with dark gray; caudal fins heavily blotched with grayish tan; iris orange-tan peripherally, red centrally (Pl. 15).