BIVALVES. 61 
frequently used by the ingenious Chinese as a sub- 
stitute for window glass. 
The excessive weight and thickness of the pon- 
derous Gaper (Mya ponderosa) indicate that it is 
found in rapid rivers, and cataracts; in short, shells 
of this division are generally thick, and their inha- 
bitants, which hide themselves in sand and mud, 
constitute a large proportion of the food of birds and 
land animals in some inhospitable regions of the 
globe. They abound in that part of the Congo 
territory, through which the Zaire flows into the 
southern Atlantic, and here they are eagerly sought 
for by the natives, who assemble for this purpose 
with their canoes, in companies of three or four 
hundred. Considerable numbers are also taken by 
the women, in scoop nets made with the fibres of 
creeping plants, or from the herbaceous cotton, which 
is common on the Congo. In some parts of the 
river they are caught in baskets placed along the 
water’s edge; in others, by means of poisonous 
plants. 
There is One, my friend, whom greatness cannot 
overpower, nor minuteness perplex. The tall um- 
brageous trees that clothe the banks of the rapid 
Zaire—the numerous islands that rise above the 
water, mantled with thick mangroves, or covered 
with Egyptian papyrus, resembling at a distance 
