Chap. I. MAPIRI. 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 



