Chap. L 
MAPIRf. 
27 
less kinds of Dipterous and Hymenopterous insects 
' appear simultaneously with the flowers. This season 
might be considered the equivalent of summer in 
temperate climates, as the bursting forth of the foliage 
in February represents the spring ; but under the 
equator there is not that simultaneous march in the 
annual life of animals and plants, which we see in high 
latitudes ; some species, it is true, are dependent upon 
others in their periodical acts of life, and go hand-in- 
hand with them, but they are not all simultaneously 
and similarly affected by the physical changes of the 
seasons. 
I will now give an account of some of my favourite 
collecting places in the neighbourhood of Santarem, 
incorporating with the description a few of the more 
interesting observations made on the Natural History 
of the localities. To the west of the town there was a 
pleasant path along the beach to a little bay, called 
Mapiri, about five miles within the mouth of the Tapajos. 
The road was practicable only in the dry season. The 
river at Santarem rises on the average about thirty feet, 
varying in different years about ten feet ; so that in the 
four months, from April to July, the water comes up to 
the edge of the marginal belt of wood already spoken of. 
This Mapiri excursion was most pleasant and profitable 
in the months from January to March, before the rains 
become too continuous. The sandy beach beyond the 
town is very irregular ; in some places forming long 
spits on which, when the east wind is blowing, the 
waves break in a line of foam ; at others receding to 
