The prevomer is short and separated anteriorly from the premaxillary and maxillary by cartilage. The posterior margin of the prevomer has a bony articulation with the sphenethmoid. Each prevomer bears five to seven teeth. The palatine is small and edentate. The anterior end of the parasphenoid is narrow (more pointed than in _Hyla boulengeri_). The pterygoid is slender and well developed (Fig. 5A). [Illustration: Fig. 5. Dorsal views of the skulls of (A) _Hyla foliamorta_ (KU 77687) and (B) _H. elaeochroa_ (KU 68289), × 3.] _Natural History._--_Hyla foliamorta_ inhabits lowland forests in eastern Panamá and breeds in temporary ponds. Males have been observed calling from grasses, bushes, and emergent vegetation near temporary ponds and ditches along roads. William E. Duellman informed me that he found a breeding congregation of this species in June near Chepo, Panamá, where males were calling from spiny palms at the edge of a woodland pond. Fouquette (1958) found calling males in May, August, and September near Miraflores Locks, Canal Zone. Calling stations vary from one to two meters above ground. No clasping pairs have been found; only one female is known (KU 101589, from 8 km NE Tocumen, Panamá); this gravid individual was collected in early June. The mating call of _Hyla foliamorta_ consists of one pulsed, low-pitched, moderate trill of about O.5 second duration. Each note is repeated at intervals of 5 seconds to a few minutes. The notes have about 50 pulses per second, a fundamental frequency of 56 cycles per second and a dominant frequency of about 3000 cycles per second (Table 2, Pl. 3B). Egg deposition sites are unknown. No information is available concerning early development, and little is known about the breeding season of _Hyla foliamorta_. Probably its breeding activities are restricted to the rainy months. _Tadpoles._--Eight tadpoles were collected from a weedy temporary pond near Chepo, Panamá, in early June. A typical tadpole in stage 35 of development (KU 104244) has a body length of 9.5 mm., tail length of 25.0 mm., and a total length of 34.5 mm. Other characters are as follows: depth of tail equal to length of body; body deeper than wide; distance between eye and nostril equal to distance between eye and spiracle; mouth anteroventral; median part of upper lip bare; rest of lip having one row of papillae; a few other rows of small papillae at corners of mouth; tooth rows 2/3; first upper row entire, second upper row interrupted medially, shorter than first; lower rows shorter than upper rows, third shortest; beak moderately robust; spiracle nearer eye than anus; anal tube short, aperture not extending to border of ventral fin; caudal musculature slender, extending to tip of pointed tail; dorsal fin extending onto body (Table 4). TABLE 4.--Sizes of Tadpoles of _Hyla foliamorta_ in Relation to Developmental Stages. (Means in parentheses below observed ranges; measurements in mm.)