All specimens were found beneath litter on the forest floor. All are males having 202 to 211 (average 205) ventrals, 53 to 56 (54.6) caudals, and 34 to 48 (41) primary black rings on the body. There are no yellow rings, and black spots in the red interspaces tend to form secondary black rings (Fig. 6b), the same as in _Pliocercus euryzonus aequalis_. The local name is _coral_ or _coralillo_. =Bothrops atrox asper= (Garman) 15 km. NW of Chinajá, 1; Sayaxché, 1. Although we found only two specimens, natives and workmen at the camp at Chinajá stated that the _barba amarilla_, as this snake is known locally, had been abundant when the camp had been established less than two years before our visit. =Bothrops nasutus= Bocourt 12 km. NW of Chinajá, 1. This specimen, a male having a total length of 415 mm., was found on the forest floor. The dorsum is brown with dark brown blotches separated middorsally by a narrow orange-tan stripe extending from the nape to the base of the tail. The belly is grayish tan with white flecks on the lateral edges of the ventrals. The local name is _nahuyaca_. =Bothrops nummifer nummifer= (Rüppell) 15 km. NW of Chinajá, 2; Sayaxché, 1. Two individuals were found on the forest floor, and one adult, having a total length of 953 mm., was removed from the stomach of a large _Drymarchon corais melanurus_. There is considerable variation in color and pattern. A juvenile (KU 58104), having a total length of 332 mm., has a tan dorsum with 19 interconnected dark brown, diamond-shaped, middorsal blotches, the lateral extensions of which are black; the belly is a cream-color with brown squares. An adult female (KU 55706), having a total length of 779 mm., has a dorsal coloration like the preceding specimen, except that the lateral extensions of the dorsal blotches are brown; the belly is a uniform cream-color. A second adult female (KU 55707), having a total length of 953 mm., has a brown dorsum with 21 interconnected black, diamond-shaped, middorsal blotches, the lateral extensions of which are black; the belly is a cream-color with black squares. The local name for this species is _braza de piedra_. =Bothrops schlegeli schlegeli= (Berthold) Paso Subín, 1. This specimen was taken from the thatched roof of a house at the edge of the forest and contained the remains of a small mammal. The local name is _nahuyaca_. HYPOTHETICAL LIST OF SPECIES Listed below are thirteen species that have not been found in southern El Petén but that probably occur there.