VALLEY OF THE AMAZONS. 
191 
I saw but few and small butterflies, and beetles 
were still more rare. The most numerous 
insects were the dragon-flies, — some with 
crimson bodies, black heads, and burnished 
wings ; others with large green bodies, crossed 
by blue bands. Of land shells I saw but one 
creeping along the reeds; and of water shells 
I gathered only a few small Ampullariae. 
Having ascended the river to a point nearly 
on a line with the serra, I landed, and struck 
across the Campos on foot. Here I entered 
upon an entirely different region, — a dry, 
open plain, with scanty vegetation. The most 
prominent plants were clusters of cactus and 
curua palms, a kind of stemless, low palm, 
with broad elegant leaves springing vase-like 
from the ground. In these dry, sandy fields, 
rising gradually toward the serra, I observed 
in the deeper gullies formed by the heavy 
rains the laminated clays which are every¬ 
where the foundation of the Amazonian strata. 
They here presented again so much the char¬ 
acter of ordinary clay slates, that I thought 
I had at last come upon some old geological 
formation. Instead of this I only obtained 
fresh evidence that, by baking them, the burn- 
