=San Jose=: Bajos de Jorco, KU 91813 (tadpoles); Escazu, KU 34863, 34869-75, USC 813; between Monrovia and La Hondura, +- 0.5 km. N Santa Rosa, USC 302 (2); Paso Ancho, Rio Jorco, UMMZ 122649 (6), USC 530 (3); Rio Jorco, near Desamparados, KU 91757-65, 91796-7, 91820-3 (skeletons), USC 228, 513, 7117 (7); Rio Peje, 10 km. SSE San Isidro el General, USC 7115 (3); Rio Tirivi, MCZ 7972; San Isidro el General, CNHM 101096, KU 28201, 32989, UMMZ 72024; 15 km. WSW San Isidro el General, KU 64245-56, 68473 (tadpoles), 68474 (young), 68475 (tadpoles), 86516, 91754-6, 91793-5, USC 7097 (6); 17.1 km. WSW San Isidro el General, USC 6047; 18 km. WSW San Isidro el General, USC 689; 20 km. WSW San Isidro el General, KU 64257-9, 64260 (skeleton), 68468 (young), 68469 (tadpoles), 68470 (young), 68471-2 (tadpoles), 68476 (young), 68633-4 (skeletons), 91751-3; San Jose, AMNH 7501-4, USC 298; Santa Rosa, Rio Virilla, USC 7145. PANAMA: =Chiriqui=: Rio Jacu, 5.8 km. ESE Paso Canoas, KU 91905. "Veraguas," ZMB 3141 (2). ANALYSIS OF MORPHOLOGICAL CHARACTERS Osteology In attempting to assay the taxonomic significance of skeletal differences we are faced with a dearth of data on the skeletons of frogs in general and hylids in particular. Recent reviews by Brattstrom (1957) and Hecht (1962, 1963) have been concerned with general salientian classification and phylogeny, principally at the family level. Savage and Carvalho (1953), Griffiths (1959), and Baldauf (1959) used osteological characters in determining the taxonomic status of the families Pseudidae, Brachycephalidae, and Bufonidae, respectively. Carvalho (1954) presented osteological evidence for the generic separation of New World microhylids. Zweifel (1956) and Tihen (1962) used osteological characters at the levels of the species-group and species in their respective studies on _Scaphiopus_ and _Bufo_. Little has been recorded about the skeletons of the hylids. Goin (1961) mentioned dentigerous elements and cranial co-ossification in his synopsis of the genera of hylids. Copland (1957) in his review of the _Hyla_ of Australia, Funkhouser (1957) in her revision of _Phyllomedusa_, and Zweifel (1958) in his review of _Nyctimystes_ did not consider skeletal characters. Some osteological studies on hylids have yielded worthwhile information. Mittleman and List (1953) used osteological characters in defining the genus _Limnaoedus_: Starrett (1960) used cranial characters in combination with jaw musculature in defining the genus _Smilisca_, and Duellman (1964) used cranial characters in delimiting the _Hyla bistincta_ group. Brief descriptions of cranial structure were given for _Phrynohyas_ (Duellman, 1956) and _Ptychohyla_ (Duellman, 1963a); specific and sexual differences in the skulls of _Hyla chaneque_ and _Hyla taeniopus_ were pointed out by Duellman (1965). Stokely and List (1954) described early cranial development in the hylid _Pseudacris triseriata triseriata_.