48 
SANTAREM. 
Chap. L 
of 500 or 600 feet, and its ascent is excessively fatiguing 
after the long walk from Santarem over the campos. I 
tried it one day, but did not reach the summit. A dense 
growth of coarse grasses clothed the steep sides of the 
hill, with here and there a stunted tree of kinds found 
in the plain beneath. In bared places, a red crumbly 
soil is exposed ; and in .one part a mass of rock, which 
appeared to me, from its compact texture and the ab- 
sence of stratification, to be porphyritic ; but I am not 
Geologist sufficient to pronounce on such questions. 
Mr. Wallace states that he found fragments of scoriae, 
and believes the hill to be a volcanic cone. To the 
south and east of this isolated peak, the elongated 
ridges or table-topped hills attain a somewhat greater 
elevation. 
The forest in the valley is limited to a tract a few 
hundred yards in width on each side the different 
streams : in places where these run along the bases of 
the hills the hill-sides facing the water are also richly 
wooded, although their opposite declivities are bare or 
nearly so. The trees are lofty and of great variety ; 
amongst them are colossal examples of the Brazil nut 
tree (BerthoUetia excelsa), and the Pikia. This latter 
bears a large eatable fruit, curious in having a hollow 
chamber between the pulp and the kernel, beset with 
hard spines which produce serious wounds if they 
enter the skin. The eatable part appeared to me not 
much more palatable than a raw potato ; but the 
inhabitants of Santarem are very fond of it, and 
undertake the most toilsome journeys on foot to gather 
a basketful. The tree which yields the tonka bean 
