202 SANTAREM. Cuap. VIII. 
live together on more friendly terms, or have some other means of 
disarming suspicion. Many Dipterous insects are also parasitic on bees, 
and wear the same dress as the species they live upon. That the dress 
of the victimisers is arranged with especial reference to their prey, 
I think is proved by what I observed at Santarem. The genera of the 
parasites here are not the same as in Europe; and when they counter- 
feit working bees, it is the peculiarly-coloured species of their own 
country that are imitated, and not those of any other region. The 
European genus Apathus, which mimics European Humble-bees, is 
not found in South America; but the common Bombus of Santarem, 
which is remarkable in being wholly of a sooty-black colour, is attended 
by a sooty-black parasite of a widely-different genus, the Eurytis fune- 
reus. Many of the little Meliponz have their counterfeits in small 
Diptera of the family Syrphidze ; and the brilliant green or blue bees 
of the country (Euglossa) have their imitators in parasitic bees of equally 
bright colours, belonging to genera unknown out of the countries where 
the Euglossze are found.* 
To the south my rambles never extended farther than the banks of 
the Irura, a stream which rises amongst the hills already spoken of, and 
running through a broad valley, wooded along the margins of the water- 
courses, falls into the Tapajos, at the head of the bay of Mapiri. All 
beyond, as before remarked, is terra incognita to the inhabitants of 
Santarem. The Brazilian settlers on the banks of the Amazons seem 
to have no taste for explorations by land, and I could find no person 
willing to accompany me on an excursion farther towards the. interior. 
Such a journey would be exceedingly difficuit in this country, even if 
men could be obtained willing to undertake it. Besides, there are 
reports of a settlement of fierce runaway negroes on the Serra de 
Mururaru,, and it was considered unsafe to go far in that direction, 
except with a large armed party. I visited the banks of the Irurd and 
the rich woods accompanying it, and two other streams in the same 
neighbourhood, one called the Panéma, and the other the Urumart, 
once or twice a week during the whole time of my residence in Santarem, 
and made large collections of their natural productions. These forest 
brooks, with their clear cold waters brawling over their sandy or pebbly 
beds, through wild tropical glens, always had a great charm for me. 
The beauty of the moist, cool, and luxuriant glades was heightened by 
the contrast they afforded to the sterile country around them. The 
bare or scantily wooded hills which surround the valley are parched by 
the rays of the vertical sun. One of them, the Pico do Irura, forms a 
nearly perfect cone, rising from a small grassy plain to a height 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 absence of stratification, to be porphyritic; but I am not 
* These are Melissa, Mesocheira, Thalestria, etc. 
