[Illustration: PLATE 13 _Ptychohyla euthysanota macrotympanum_ (KU 58049). x 2.] =Ptychohyla euthysanota macrotympanum= (Tanner) _Hyla macrotympanum_ Tanner, Great Basin Nat., 17:52-53, July 31, 1957 [Holotype.--AMNH 62141 (formerly BYU 13752) from 10 miles east of Chiapa de Corzo, Chiapas, Mexico; Robert Bohlman collector]. _Ptychohyla macrotympanum_, Duellman, Univ. Kansas Publ. Mus. Nat. Hist., 13:351, April 27, 1961. _Diagnosis._--Dorsum usually pale tan; venter white with scattered brown or black flecks; a thin white stripe on upper lip and another above anal opening; no distinct white stripe on flanks. _Description._--The following description is based on KU 58049 from Linda Vista, Chiapas, Mexico (Pl. 13). Adult male having a snout-vent length of 38.0 mm.; tibia length, 19.5 mm.; tibia length/snout-vent length, 51.3 per cent; foot length, 15.7 mm.; head length, 11.8 mm.; head length/snout-vent length, 31.1 per cent; head width, 11.7 mm.; head width/snout-vent length, 30.8 per cent; diameter of eye, 3.8 mm.; diameter of tympanum, 2.1 mm.; tympanum/eye, 55.2 per cent. Snout in lateral profile nearly square, slightly rounded above, and in dorsal profile bluntly rounded; canthus pronounced; loreal region concave; lips thick, rounded, and slightly flaring; nostrils protuberant; internarial distance, 3.1 mm.; top of head flat; interorbital distance, 3.8 mm., and approximately a fourth broader than width of eyelid, 3.1 mm. A moderately heavy dermal fold from posterior corner of eye above tympanum to point above insertion of forelimb, covering upper edge of tympanum; tympanum round, its diameter equal to its distance from eye. Forearm moderately robust, having a distinct dermal fold on wrist; dermal fold, but no row of tubercles along ventrolateral surface of forearm; pollex only slightly enlarged, bearing triangular patch of small horn covered spines (94 on right, 100 on left); fourth finger slightly longer than second; subarticular tubercles round, none bifid; discs moderate in size, that of third finger equal to diameter of tympanum; vestige of web between first and second fingers; other fingers one-third webbed. Heels broadly overlap when hind limbs adpressed; tibiotarsal articulation reaches to middle of eye; weak tarsal fold on distal two-thirds of tarsus; inner metatarsal tubercle large, elliptical, and flat; outer metatarsal tubercle small and round; no dermal fold from heel to disc of fifth toe; subarticular tubercles round; length of digits from shortest to longest 1-2-5-3-4; third toe webbed to base of disc; fifth toe webbed to middle of penultimate phalanx; fourth toe webbed to proximal end of penultimate phalanx; no fold of skin from inner metatarsal tubercle to base of disc on first toe; discs much smaller than on fingers. Anal opening near upper edge of thighs; short anal flap bordered above by thin dermal fold; small tubercles and heavy dermal fold lateral to