AQUATIC INSECTS 



257 



to make a dash in and out through the showers that 

 fall about the large brass lamps over the counter, when 

 they want to make a purchase. The species are certainly 

 not indigenous to the eastern side of the river ; the hosts 

 soon disappear ; those which cannot get back must perish 

 helplessly, for the soil, vegetation, and climate of the 

 Santarem side are ill suited to the inhabitants of the 

 opposite shore. 



The pools I have mentioned were tenanted by a con- 

 siderable variety of insects ^. I found also a very large 

 number, chiefly of carnivorous land-beetles under the 

 pebbles and rejectamenta along the edge of the water 

 during my many rambles. I was much struck with the 

 similarity of the dragon -flies (whose early states are 

 passed in the water) to those of Britain. A species of 

 Libellula with pointed tail, which darted about over the 

 bushes near the ponds, is very closely allied to our English 

 L. quadrimaculata. But the resemblance was greater in 

 the small, slender-bodied and slow-flying species, the 

 Agrions, which every lover of rural walks must have 

 noticed in England by river sides. There was one pretty 

 kind with a pale blue ring at the tip of the body which 

 resembled to a remarkable degree a common British 

 species. Although very near akin, neither this nor any 

 of the other kinds, were perfectly identical with European 

 ones. The strikingly peculiar dragon-flies from Tropical 

 America which are seen in our collections are denizens 

 of the forest, being bred in the shady brooks and creeks 

 in their recesses, and not in the weedy ponds of open 

 places. Som.e of these forest species are strange creatures 

 with slender bodies measuring seven inches in length ; 

 their elegant lace-work wings tipped with white or yellow. 

 They fly slowly amongst ^the trees, preying on small 



^ The water beetles found in the pools belonged to seventeen 

 genera, thirteen of which are European. Those European 

 genera which form the greater part of the pond population 

 in Coleoptera in northern latitudes, are quite absent in the 

 Amazons region : these are, Haliplus, Cnemidotus, Pelobius, 

 Noterus, Ilybius, Agabus, Colymbetes, Dyticus, and Acilius : 

 Hydropori, also, are very rare. The most common species 

 belong to the genera Hydracanthus, Copelatus, Cybister, 

 Tropisternus, and Berosus, three of which are unknown in 

 Europe. 



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