All individuals were observed on trunks of trees between heights of three and ten meters above the ground. The largest male has a snout-vent length of 81 mm. and a tail length of 155 mm.; the same measurements of the largest female are 87 and 150 mm. The streaked brown dorsum, combined with the lizards' habit of pressing the body against the trunks of trees, make this anole especially difficult to see.

Anolis humilis uniformis Cope

This small dull brown anole is a characteristic inhabitant of the forest floor, where the lizards move about in a series of quick, short hops and thus easily evade capture. Three individuals were found on small bushes, and four were on the bases of trees; otherwise, all were observed on the ground. Observations indicate that this species is active throughout the day, except during and immediately after heavy rains. The males have a deep red dewlap with a dark blue median spot.

Anolis lemurinus bourgeaei Bocourt

This moderate-sized anole characteristically inhabits the low bushes and bases of trees in the forest. Individuals were most readily observed on the buttresses of some of the gigantic mahogany and ceiba trees. When approached the lizards usually ran around the tree or ducked to the other side of the buttress; if the observer moved closer, they jumped to the ground and ran off. None was observed to ascend large trees. Some individuals were observed foraging on the forest floor; these took shelter on the bases of trees. One individual was sleeping on a palm frond at night. The adult males have a uniformly orange-red dewlap.

Anolis limifrons rodriguezi Bocourt

In dry forests and more open situations than occur at Chinajá this little anole is abundant, but in the wet forests of southern El Petén, only three specimens were found. Two were on palm fronds about two meters above the ground; the other was on a low bush. I suspect that ecologically this species overlaps A. humilis uniformis and A. lemurinus bourgeaei, but too few observations are recorded to justify a definite statement at this time.

Anolis sericeus sericeus Hallowell

This small anole is common and widespread in the Atlantic lowlands of southern México and northern Central America; usually it inhabits sub-humid regions. Consequently, its presence in the wet forests of southern El Petén was unexpected. The specimens from Chinajá were sleeping on low bushes at night, whereas the others were found on bushes by day.

Basiliscus vittatus Wiegmann

Individuals of this abundant species were most frequently seen in dense bushes along the margins of rivers or small streams. None was observed far from water. These lizards, like the anoles, are known locally as toloque.

Corythophanes cristatus (Merrem)

Three individuals were found on tree trunks; the fourth was on a thick vine about one meter above the ground. The two largest males have snout-vent lengths of 121 and 115 mm. and tail lengths of 265 and 243 mm. The largest female (KU 59603), obtained on June 28, has a snout-vent length of 125 mm. and a tail length of 247 mm. This individual contained eight ova varying in greatest diameter from 10.6 to 12.2 (average 11.1) mm. Also present are numerous ovarian eggs having diameters up to about 3.5 mm.

One of the large males displayed a defensive behavior prior to capture. When first observed the lizard was clinging to a tree trunk about one and one-half meters above the ground. When I approached, the lizard turned its flanks towards me; then it flattened the body laterally, extended the dewlap, opened its mouth, and made short rushing motions. When touched it bit viciously. On the ground these lizards have a rather awkward bipedal gait that is much slower than in Basiliscus vittatus.

In life an adult male (KU 55804) was reddish brown dorsally with dark chocolate brown markings; the venter was creamy white, and the iris was dark red. The natives call this lizard piende jente.

Iguana iguana rhinolopha Wiegmann

The iguana, as this lizard is called locally, seems to be uncommon in the forested areas of southern El Petén. Possibly this is due to the fact that the flesh of this lizard is relished as food by the natives. My two specimens were in large trees at the edge of the river.

Laemanctus deborrei Boulenger

On June 26 a female having a snout-vent length of 129 mm. and a tail length of 502 mm. was found on a bush in the forest. The lizard, when approached, faced the collector and opened its mouth. In life the dorsum was bright green; the lateral stripe was white, and the iris was yellowish brown. This specimen contained four ova having lengths of 13.4 to 14.2 (average 13.9) mm.

On June 30 at Toocog five white-shelled eggs were found in a rotting log. Measurements of the eggs are—length, 23.5 to 25.0 (average 24.2) mm.; width, 15.0 to 15.5 (average 15.4) mm. These eggs hatched on August 30. The five young had snout-vent lengths of 43 to 45 (average 44) mm., and tail lengths of 137 to 140 (average 138) mm. In life the hatchlings had a dull dark green dorsum, pale bright green venter and stripes on head, and reddish brown iris. In preservative the hatchlings are creamy tan above with five or six square dark brown blotches middorsally.

The natives consider this lizard to be one of the anoles; consequently, it is known as toloque.

Lepidophyma flavimaculatum flavimaculatum Duméril

Individuals were found beneath logs on the forest floor or moving about in the litter on the forest floor. One was observed crawling across a trail during a heavy rain. In some adults the tan dorsal spots are large and distinct; in others the spots are small and indistinct. Two juveniles, apparently recent hatchlings, were found on June 28 and July 5. These specimens have snout-vent lengths of 29 mm. and tail lengths of 38 and 41 mm.

Eumeces schwartzei Fischer

One specimen (KU 59551) was found on the forest floor at midday; it is an adult female having a snout-vent length of 125 mm. and a tail length of 210 mm. This specimen is larger than those recorded by Taylor (1936:99) and extends the known range of the species south of Ramate, approximately 125 kilometers south-south-westward to Chinajá.

Eumeces sumichrasti (Cope)

One adult male having a snout-vent length of 82 mm. was found beneath a palm frond on the forest floor. In life the dorsum was dull brown; the chin was cream; the belly was yellow, and the underside of the tail was orange. A juvenile having a black body, yellow dorsal stripes, and a bright blue tail was observed on the forest floor.

Scincella cherriei cherriei (Cope)

All individuals of this lizard were found in the leaf litter on the forest floor; many escaped capture. In life the tail is dull bluish gray. The number of dorsal scales varies from 59 to 61 (average 60); thus, these specimens fall within the range of variation of S. cherriei cherriei, and thereby differ from S. cherriei stuarti to the west and S. cherriei ixbaac to the north.

Ameiva festiva edwardsi Bocourt

This abundant terrestrial lizard, locally called lagartijo, is found throughout the forest. A juvenile obtained on March 14 at Sayaxché has a snout-vent length of 42 mm. and a prominent umbilical scar. Other juveniles were observed at Chinajá in February and March, thereby indicating that the young probably hatch in the early part of the year. Juveniles have bright blue tails.

Celestus rozellae Smith

Two specimens were obtained from trees by workmen in February. These lizards have snout-vent lengths of 70 and 83 mm. and tail lengths of 133 and 135 mm. There are 21 and 23 lamellae beneath the fourth toe; each has 31 longitudinal rows of scales around the body.

Boa constrictor imperator Daudin

All specimens were found on the forest floor. One individual was found in combat with a large Drymarchon corais melanurus. Apparently, the Drymarchon was attempting to devour the Boa, which had a total length of 1683 mm. Locally this snake is called masacuata; it is one of the few snakes believed by the local inhabitants to be non-poisonous.

Clelia clelia clelia Daudin

One specimen is represented only by the head; the snake was killed on the forest floor by workmen. Another individual was found in a pool of water at the base of a limestone outcropping in the forest; this specimen (KU 58167) is a female having a body length of 2220 mm. and a total length of 2634 mm. This snake contained 22 ova averaging 56 × 23 mm. Both specimens were uniform shiny black above and cream-color below. The local name is sumbadora.

Coniophanes bipunctatus bipunctatus (Günther)

This snake was found on the forest floor by day; it is a male having 130 ventrals, an incomplete tail; cream-colored belly, and a pair of large brown spots on each ventral scute.

Coniophanes fissidens fissidens (Günther)

This male specimen was found beneath a rock in a sink hole. It has 122 ventrals and 77 caudals. A narrow temporal stripe extends along the upper edge of the anterior temporal and the lower edge of the upper secondary temporal. The belly is ashy white with a pair of small black spots on each ventral.

Coniophanes imperialis clavatus (Peters)

All specimens were found on the forest floor by day. These small snakes are capable of rapid movement and quickly disappear in the litter on the ground. Two individuals evaded capture. The belly is creamy white anteriorly and vermillion red posteriorly.

Dryadophis melanolomus laevis (Fischer)

These snakes, locally known as sumbadora, were found on the forest floor; two others were seen, but escaped. The variation in coloration has been a source of confusion in this species in northern Central America (see Stuart, 1941:86). All of the present specimens are males: KU 55709 has 178 ventrals, 121 caudals, and a total length of 914 mm.; the dorsum is olive-tan with six darker cross-bars on the neck; the belly is creamy white. KU 58160 has 188 ventrals, 123 caudals, and a total length of 1365 mm.; the dorsum is uniform olive-brown, except that some dorsal scales at midbody have black anterior borders like D. melanolomus melanolomus has in the Yucatán Peninsula; the venter is pale yellow. KU 58158 has 179 ventrals, 122 caudals, and a total length of 723 mm.; the dorsum is rich chocolate brown with eight dark cross-bars on the neck; the belly is bright orange.

Stuart (1941a:87) stated that in life two distinct color phases were observed in specimens collected by him in Alta Verapaz, Guatemala. One had an olive-brown dorsum and the other, a reddish orange dorsum. Stuart made no mention of variation in the color of the venter. Similar variation is known in D. melanolomus alternatus in Costa Rica, where some individuals have orange-red venters. This color phase has been recognized as a distinct species, Dryadophis sanguiventris, by Taylor (1954:722). Examination of 18 specimens from Costa Rica shows no differences in scutellation, nor geographic segregation of two populations. I am convinced that the red-bellied Dryadophis in Costa Rica, like those in Guatemala, represent a color phase of the subspecies inhabiting those areas and that Dryadophis sanguiventris Taylor is a synonym of Dryadophis melanolomus alternatus (Bocourt).

Drymarchon corais melanurus (Duméril, Bibron and Duméril)

The specimen from Sayaxché was found at the edge of a clearing in the forest; that from 15 kilometers northwest of Chinajá was found on the forest floor coiled with a Boa constrictor imperator, which the Drymarchon apparently was trying to eat. The Drymarchon is a giant specimen having a total length of 2950 mm. (see Duellman, 1961:368). The Boa with which it was coiled has a total length of 1683 mm. I was attracted to the snakes by a loud thrashing noise. When I approached the writhing mass, the snakes separated, but I was able to see that the Drymarchon had its teeth firmly imbedded in the posterior part of the head of the Boa. From the Drymarchon I forced the regurgitation of a recently ingested Bothrops nummifer nummifer having a total length of 953 mm. These observations show that the snake-eating capabilities of Drymarchon can hardly be over-estimated.

In both Drymarchon the anterior one-half of the body is olive-tan, which changes to bluish black posteriorly. The local name is sumbadora.

Drymobius margaritiferus margaritiferus (Schlegel)

All individuals were obtained in clearings in the forest by day in the rainy season. Two individuals each contained a Similisca baudini and another contained a Bufo valliceps valliceps. Locally this snake is known by the appropriate name of ranera.

Imantodes cenchoa leucomelas Cope

With the exception of one that was found dead in camp, all individuals were taken from low vegetation by day. The dorsum is creamy tan with 28 to 35 (average 32) chocolate brown blotches, and the venter is ashy white with small brown flecks. Three males have 238 to 248 (average 244) ventrals and 148 to 154 (average 151) caudals; one female has 239 ventrals and 142 caudals. The largest specimen, a male, has a body length of 660 mm. and a total length of 943 mm.

Lampropeltis doliata polyzona Cope

One female (KU 57156) having 230 ventrals and 54 caudals was found on the forest floor by day. This individual has a black snout with a white bar across the nasals and prefrontals, a white spot in the middle of the frontal, and a white band across the temporals and parietals that is bordered posteriorly by a black band. There are 28 white and 28 red rings on the body. The tips of the red scales are darkened. The black rings between the white and red rings are not so expanded as to interrupt the white rings dorsally as in L. doliata abnorma as identified by Stuart (1948:70). Locally this snake, like all red, black, and white or yellow banded snakes, is called coral or coralillo.

Leptodeira frenata malleisi Dunn and Stuart

This specimen, a male having 173 ventrals and 69 caudals, was found beneath the bark on a log in the forest. In life the dorsum was pinkish tan with 36 chocolate brown blotches on the body; the venter was rosy pink.

Leptodeira septentrionalis polysticta Günther

If numbers of specimens are indicative of abundance, this is the most common snake in southern El Petén. All were found at night in the rainy season. At a pond in the forest at Toocog these snakes were observed on low vegetation, on the ground, and in the water. Evidently they congregate at breeding choruses of frogs. One Leptodeira contained a Smilisca baudini and another contained eggs of Phyllomedusa callidryas taylori. The natives call this snake nahuyaca.

Leptophis ahaetulla praestans (Cope)

Both specimens were obtained from trees when they were felled. One individual (KU 55716) has a body length of 1345 mm. and a total length of 2035 mm. In life the entire snake was uniform bright green; the eye was yellow. In preservative the dorsum is dark blue, and the venter is green.

Leptophis mexicanus mexicanus Duméril, Bibron and Duméril

All specimens came from low trees in the forest. The largest specimen is a male having a body length of 724 mm. and a total length of 1236 mm. In life the middorsum was a golden tan; the top of the head was a vivid green. One individual had ingested a Smilisca baudini. The local name is bejuquillo.

Ninia sebae sebae (Duméril, Bibron and Duméril)

This specimen, a male having 144 ventrals and 55 caudals, was found beneath bark on a log in the forest. There is a black band five scales in length on the nape followed posteriorly by a red band six scales in length and then by a complete black band one and one-half scales in length. The rest of the body is dull red with 16 incomplete black bands one to one and one-half scales in length on the anterior two-thirds of the body.

Oxybelis aeneus aeneus (Wagler)

One individual was found in a low tree; the other was in a bush. Both specimens are males; the largest has a body length of 754 mm. and a total length of 1286 mm. Bogert and Oliver (1945:388) distinguished O. aeneus aeneus in Central and South America from O. aeneus auratus in México in that the diameter of the eye is more than the length of the internasal, whereas in O. aeneus auratus the diameter of the eye is less than the length of the internasal. Stuart (1958:27) stated that on the basis of this character three specimens from Tikal in northeastern El Petén definitely were O. aeneus aeneus. Of the present specimens from southern El Petén, one has an internasal:eye ratio of 1.08; the other has a ratio of 0.87. A careful review of these snakes is needed to verify the validity of the characters used to separate the subspecies and to determine areas of intergradation. The local name for the vine-snake is bejuquillo.

Pliocercus euryzonus aequalis Salvin

These specimens are tentatively referred to P. euryzonus. KU 57160 is a female having 130 ventrals, 87 caudals, and 23 black rings on the body; KU 58150 is a juvenile having 128 ventrals, 79 caudals, and 27 black rings on the body. In both specimens the tip of the snout is yellow; a broad yellow band on the parietals and temporals is bordered posteriorly by a black band on the nape. The black rings on the body are not bordered by yellow, but black rings on the tail have yellow borders ventrally. In the red interspaces between the black rings, black flecks and spots, especially posteriorly, tend to form secondary black rings (Fig. 6a). According to Stuart (1948:71), P. euryzonus aequalis has 25 to 27 black rings on the body, whereas P. elapoides salvini, which also occurs in El Petén, has 15 to 23 black rings.

The specimen from the Río San Román contained a partly digested Bolitoglossa moreleti mulleri. Locally Piocercus is called coral or coralillo.

Pseustes poecilonotus poecilonotus (Günther)

Two juveniles were on the forest floor; one juvenile and an adult were on low bushes. The juveniles have a tan dorsum with reddish brown blotches; the belly is gray, and the iris is cream-color above and brown below. The one adult is olive-brown above and creamy white below on the anterior three-fourths of the body; posteriorly it is black above and below. There are no paravertebral dark stripes nor pale spots on the dorsal scales.

Two specimens (one juvenile and the adult) when encountered compressed the anterior part of the body laterally and struck repeatedly. Locally the adults are called sumbadora.

Sibon dimidiata dimidiata (Günther)

Both snakes were obtained from trees when they were felled. In life the dorsum was pinkish orange with dark chocolate brown blotches narrowly edged with black.

Sibon nebulata nebulata (Linnaeus)

This specimen, a male having a body length of 544 mm. and a tail length of 198 mm., was found in a felled tree. In life the belly was pink and black; the dorsal black blotches were narrowly outlined with pink.

Spilotes pullatus mexicanus (Laurenti)

This large snake, locally called mica, seems to be equally at home on the ground and in low trees and bushes. It is fast moving for a large snake; two individuals escaped capture. The natives said that this snake eats other snakes, but examination of stomachs revealed no supporting evidence.

Stenorrhina degenhardti (Berthold)

This specimen, a female having 158 ventrals, 37 caudals, and a total length of 489 mm., was found on the forest floor. On the olive-brown dorsum are 27 irregular, narrow, dark brown, transverse bands. The head is uniform olive-brown; the chin and labials are cream-color. The venter is cream-color with a row of brown spots forming a midventral stripe. A large spider was found in the stomach.

I have refrained from assigning a subspecific name to this snake. Cursory examination of specimens from throughout México and Central America reveals a bewildering array of variation in coloration that suggests that the subspecies mexicanus is not recognizable, or that two species occur sympatrically in parts of southern México and northern Central America.

Tretanorhinus nigroluteus lateralis Bocourt

A single male having 136 ventrals, 75 caudals, and a total length of 407 mm. was found by a stream in camp. The dorsum is pale grayish tan with 34 pairs of small chocolate brown spots, some of the anterior ones of which are connected across the back. A cream-colored lateral stripe is on the third and fourth dorsal scale-rows anteriorly and the second and third rows posteriorly. The lower dorsal scale rows are black. The venter is dark grayish brown with cream-colored flecks anteriorly and creamy gray posteriorly where the dark color is restricted to the midventral region and the lateral edges of ventrals and first dorsal scale-row.

Xenodon rabdocephalus mexicanus Smith

Both individuals were found on the forest floor. An adult male having a total length of 420 mm. has a cream-colored venter with brown flecks. A juvenile having a total length of 172 mm. has a creamy white belly with black crossbands.

At the suggestion of L. C. Stuart, I am following Schmidt (1941:501) in placing X. mexicanus as a subspecies of X. rabdocephalus.

Micrurus affinis apiatus (Jan)

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)

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

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)

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)

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

SUMMARY

LITERATURE CITED

Duellman, W. E.

Dunn, E. R. and Emlen, J. T.

Firschein, I. L. and Smith, H. M.

Lundell, C. L.

Neill, W. T. and Allen, R.

Sapper, K.

Schmidt, K. P.

Simpson, G. G.

Smith, H. M. and Taylor, E. H.

Stuart, L. C.

Taylor, E. H.

Taylor, E. H. and Smith, H. M.