D. DESCRIPTIVE LIST OF MIDDLE AMERICAN BIOTA (CENTRAL 

 MEXICO TO THE AMAZON) 



BY FORREST SHRBVE AND V. E. SHELFORD 



(Names in parenthesis are synonyms used in published works or in the manu- 

 scripts submitted) 



1. LUXURIANT TROPICAL RAIN-FOREST 

 BIOTA (RAIN-FOREST; LOWLAND TROP- 

 ICAL FOREST; HEAVY FOREST; HEAVY 

 HUMID FOREST) 



This forest occupies regions with 

 uniform mean monthly temperature and 

 a heavy and well distributed rainfall. 

 The forest is composed of a great number 

 of different species and genera of trees 

 of different stature and of shrubs and 

 vines. The dominant trees are ever- 

 green, or nearly so, and their leaves are 

 relatively small and thick, while those 

 of the subordinate trees are broad and 

 thin. 



The animal life is also represented by 

 a vast number of species. Termites 

 which build nests on trees, leaf carrying 

 ants, military ants and gaudy butter- 

 flies characterize the insect population. 

 Frogs and lizards are numerous. The 

 snakes include some of the constrictors 

 and poisonous coraline and crotaline 

 species. Most of the birds are of com- 

 mon neotropical types, many being large, 

 grotesque or gaudy. Monkeys are most 

 numerous here many rarely coming to 

 the ground. Cats large and small, 

 squirrels, and opossums are plentiful, 

 Arboreal anteaters and sloths are char- 

 acteristic. Tapirs are nearly always 

 present. 



2. DRIER TROPICAL RAIN-FOREST BIOTA 



(LOWLAND RAIN-FOREST) 



This type of forest is similar to the 

 luxuriant tropical Rain-Forest, but is 

 not so heavy, the trees are not usually so 

 tall nor so numerous in species, and the 



abundance of epiphytes and lianas 

 depends upon local conditions, tending 

 to be less numerous than in the Luxu- 

 riant Tropical Rain-Forest. The ani- 

 mal life is similar to that of the luxuriant 

 forest but poorer in species and with 

 many species different. 



3. ARID DECIDUOUS FOREST BIOTA 

 (MONSOON FOREST; SEMI- 

 DECIDUOUS FOREST) 



This forest is similar to the drier rain 

 forest in the wet season, but exhibits 

 partial leaf fall in the dry season. It 

 is rich in epiphytes of bromeliad type, 

 but relatively poor in lianas. The 

 shrubs are chiefly evergreen. 



The monkeys, opossums, and ar- 

 boreal anteaters drop out or become 

 much less numerous than in the tropical 

 rain forest. Peccaries, forest rabbits, 

 foxes, and deer are more numerous. It 

 must be borne in mind, however, that 

 trees adjacent to streams often retain 

 their leaves and that monkeys, tapirs, 

 etc., ordinarily found in rain forest 

 may occur here. In general, however, 

 the species in the deciduous forest 

 proper are quite different in the case of 

 animals. 



4. DECIDUOUS THORN FOREST BIOTA 



(XEROPHYLOUS FOREST; THORN 

 FOREST; CAATINGA) 



Deciduous Thorn Forest occupies 

 some of the more arid portions of South 

 America. It consists of a more or less 

 close stand of large shrubs, small trees 

 and succulents. The majority of the 

 dominant plants are leafless in the dry 



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