194 SANTAREM Cuap. VIII 
expanse of dark water, the farther shore of the Tapajos being barely 
visible as a thin grey line of trees on the horizon. ‘The transparency of 
air and water in the dry season when the brisk east wind is blowing, 
and the sharpness of outline of hills, woods, and sandy beaches, give a 
great charm to this spot. 
The little pools along the beach were tenanted by several species of 
fresh-water mollusks. The most abundant was a long turret-shaped 
Melania, which swarmed in them in the same way as Limnzez do in 
ponds at home. I found no Limnza, nor indeed any European genus 
of fresh-water mollusk, in the Amazons region. After the first storm 
of February the coast is strewn with large apple-shells (Ampullaria). 
They are not inhabitants of the pools on this side of the river, but are 
involuntary visitors, being driven across by the wind and waves with 
masses of marsh plants from the low land of the opposite shore. A 
great many are dead shells, and more or less worn. In showery weather 
I seldom came this way without seeing one or more water snakes of 
the genus Helicops. They were generally concealed under the heaps 
of thick aquatic grasses cast ashore by storms ; and when exposed, 
always made off straight for the water. They glided along with such 
agility that I rarely succeeded in capturing one, and on reaching the 
river they sought at once the bottom in the deepest parts. I believe 
these snakes are swept from the marshy land of the western shore with 
the patches of grass and the Ampullariz just mentioned. Other reptiles 
and a great number of insects are blown or floated over in the same 
way by the violent squalls which occur in January or February. None 
of the species take root on the Santarem side of the river. Sometimes 
myriads of Coleopterous insects, belonging to about half a dozen kinds, 
are blown across, and become perfect pests to the townspeople for 
two or three nights, swarming about the lights inevery chamber. They 
get under one’s clothing, or down one’s back, and pass from the oil- 
lamp on to the furniture, books and papers, smearing everything they 
touch. The open shops facing the beach become filled with them, and 
customers have 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 helpless!,, 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 considerable 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 
* 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, Colym- 
betes, 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. 
