NARRATIVE OF THE EXPEDITIONS 7 
No real hardship is involved in making this journey, thanks to the series of 
government tambos, or shelter houses, at convenient distances, which cater 
very well to those who come well recommended. This is otherwise a region 
entirely devoid of inhabitants. 
Ten days were spent at Puerto Bermudez. Two days by canoe brought the 
party to a point on the Pichis to which the steam mail launch could ascend. 
Thenceforward travel was chiefly by launches, mail and commercial, which 
abound in Loreto; the shorter trips into tributary streams and lakes were 
made in dugouts. A month was devoted to the vicinity of Contamana on the 
lower Ucayali, a fortnight to the Puinahua and Pacaya, and an equal period 
to the region of Iquitos. The markets of Iquitos are in season very well 
supplied with fresh fish of great variety. Another month was spent in cruising 
the upper Maranon from Iquitos to the Pongo de Manseriche, and the tribu- 
taries Tigre and Morona. A three-week sojourn in and about Yurimaguas 
allowed an examination of the lower Huallaga, the third of four great rivers of 
Peruvian Amazonia. I had during the Irwin Expedition collected on the 
upper portion of this river. 
These streams, the Ucayali, Maranon, and Huallaga, are comparable in 
size to the Ohio at flood stage. All arise in the Andes and form a vast con- 
fluent flood plain parallel to the mountains, and 500-600 miles in extent. 
Though 2,000—2,500 miles from the mouth of the Amazon, this plain is only 
400 feet above sea level. In all this stretch there is very little topographic 
relief. The annual fluctuation in level of the Amazon at Iquitos is 40 feet. 
The annual inundation therefore extends far inland from the rivers. Large 
numbers of cut-off lakes (cochas) with their connecting canvas form a network 
throughout the system, which becomes one body of water with the coming of 
winter rains. Most of them are dead-water bayous of varying dimensions. 
There are almost no brooks—all depressions (quebradas) only serving to receive 
the backwater of the rivers. The smaller tributary rivers vary greatly in their 
flow at all seasons, fluctuating both with the local rainfall and with the level 
of the outlet. A stream flowing very rapidly now may display almost no 
current within a few hours, or vice versa. 
The extent of the navigable portion of the streams in Peru is much greater 
than in most Brazilian streams. Many of the latter are interrupted not far 
from their mouths by impassible rapids. The Brazilian river basins are 
sharply separated from each other by chains of hills. To the Loretan the 
slightest rise 1s a cerro—mountain. Any stretch of terrain not inundated is 
an altura. Every riffle is a pongo—rapid. Within the past few years even 
the redoubtable Pongo de Manseriche, by which the Maranon breaks through 
its last chain of the Andes, has been passed by no fewer than five steam launches. 
It has always been risked by raft and canoe. 
The above conditions allow many species of fish from the lower Amazon to 
become distributed to the very foot of the Andes, and throughout oriental 
Peru. One finds many fishes extending from one extremity of Loreto to the 
other. 
With the annual subsidence of the water there is of course everywhere a 
local sorting of species according to preferred habitat. Thus in a given stream 
one may not obtain more than two, three, or half a dozen species at the same 
time. Rarely are more than this number brought up in a single haul of a seine. 
(Bates called attention to this fact seventy years ago.) The cochas usually 
produce more species, but spaced pretty well apart. To get them all one 
must draw the seine many times in various parts of the lake. The common 
