354 NOTES OF A BOTANIST chap. 
that of animals, I have been struck with the fact 
that there are certain grand features of the vegeta- 
tion which prevail throughout Cisandine America, 
within the tropics, and even beyond the southern 
tropic — features independent of the actual distribu- 
tion of the running waters, partly also of the geo- 
logical constitution, and even of the climate — to 
which the range of the larger species of Mammals 
and Birds corresponds in a considerable degree, but 
not that of any other class or tribe of animals, and 
especially not of lepidopterous Insects. These 
features depend on the prevalence of certain groups, 
or even of single species, of plants over vast areas: 
one set prevailing in the Virgin or Great Forests 
(Caa-guacu of the Brazilians, Monte Alto of the 
Venezuelans) which clothe the fertile lands beyond 
the reach of inundations, and constitute the great 
mass of the vegetation ; another in the Low or 
White Forests (Caa-tinga, Monte Bajo) — those 
curious remnants of a still more ancient and 
humbler but surpassingly interesting vegetation, 
which (especially on the Rio Negro and Casiquiari) 
are being gradually hemmed in and supplanted by 
the sturdier growth of the Great Forests, wherein 
they are interspersed like flower-beds in a shrub- 
bery ; another in the Riparial Forests (Ygapii or 
Gapo of the Brazilians, Rebalsa of the Spaniards), 
on lowlands bordering the rivers, and laid under 
water for several months in the year, where the 
trees when young, and the bushes throughout their 
existence, must have the curious property of being 
able to survive complete and prolonged submersion, 
constituting for them a species of hybernation ; a 
fourth in the Recent Forests (Caa-puera, Rastrojo), 
