LEAVE MANAOS. 345 
V 
waters, it extends over a much wider area. lu the same 
way, fishes which gather near the mouth of a rivulet, at 
the time of low waters, will be found as high as its origin 
at the period of high waters ; while fishes which inhabit 
the larger igarapes on the sides of the Amazons when they 
are swollen by the rise of the river, may be found in the 
Amazons itself when the stream is low. There is not a 
single fish known to ascend from the sea to the higher 
courses of the Amazons at certain seasons, and to return 
regularly to the ocean. There is no fish here corresponding 
to the salmon, for instance, which ascends the streams of 
Europe and North America to deposit its spawn in the cool 
head-waters of the larger rivers, and then returns to the sea. 
The wanderings of the Amazonian fishes are rather a result 
of the alternate widening and contracting of their range 
by the rise and fall of the waters, than of a migratory 
habit ; and may be compared to the movements of those 
oceanic fishes which, at certain seasons, seek the shoals 
near the shore, while they spend the rest of the year in 
deeper waters. 

" Take our shad as an example. It is caught on the coast 
of Georgia in February, on the Carolina shores a little 
later ; in March it may be found in Washington and Balti- 
more, next in Philadelphia and New York ; and it does not 
make its appearance in the Boston market (except when 
brought from farther south) before the latter part of April, 
or the beginning of May. This sequence has led to the 
belief that the shad migrates from Georgia to New England. 
An examination of the condition of these fishes, during the 
months when they are sold in our markets, shows at once 
that this cannot be the case. They are always full of roe, 
and, being valued for the table at this period, they are 
15* 
