NO. 3658 LIZARDS—RAND AND HUMPHREY 9 
mon. Canopy species, particularly Polychrus marmoratus, are seen 
here, more frequently than in older forest apparently because the 
canopy is closer to the ground. 
Clearings and edges have few species but they are sometimes ex- 
tremely abundant, particularly Z’ropidurus torquatus. These species 
are undoubtedly native in areas such as Belém, where rain forest is 
the climax vegetation, but they also occur in other major habitat areas 
such as “cerrado,” where rain forest is absent. Though the lizards 
typical of clearings disperse through and even live inside the rain 
forest (e.g., abuya), they are never abundant there. 
IGUANA en 
| ANOLIS PUNCTA POLYCHRDS 
MARMORATUS 
PLICA 7 
| rheusl RATUS 
URANOSCODON. HUMERALIS 
SUPERCILIOSA jena MABOUIAI, ORQUA 
ax 
KENTROPYX CALCAI i Me U 
TUPINAMEIS NIGROPUNCTATUS 
Ficure 1.—Habitat distribution in Belém lizards: Schematic cross section of Belém habitats 
from upland forest, with a small forest stream at left, through second growth and grassland 
to bare ground at right (each species located in area of maximum observed abundance). 
There are a number of factors that may be involved in making the 
forest the environment where the largest number of species occur. Of 
the environments in the Belém region, the forest comprises the greatest 
area, it is the most stable on any one site, and it contains the widest 
floristic diversity and probably the most numerous species of other 
animals, (These factors were all certainly true before the advent of 
modern man.) All of these may well be involved in promoting species 
diversity, and this paper provides no evidence for emphasizing or 
excluding any of them. Figure 1 suggests that the greater structural 
complexity of the forest may also be important. There are lizards in the 
forest occupying structural situations that do not exist or exist only 
rarely outside the forest. Their restriction to the forest may be, in part, 
the direct result of the fact that the forest’s more complex structuring 
provides places for the lizards to live. 
The physical structures in an environment that a lizard uses as look- 
outs, hiding places, basking spots, etc., form an important aspect of the 
ee ee 
