CONSTRUCTION OF SHELLS. 15 
utter extinction, by the depredations of sea-birds 
and rapacious fishes, while at the same time he 
spreads abroad for these a constant supply of food, 
in the desolate sites of earth or ocean which they 
are appointed to occupy ? 
The Roman naturalist noticed with admiration 
the transformation of several species of caterpillars 
from an intermediate state to that splendid investi- 
tude in the Spring, when still preserving their identity, 
and having passed from the baseness of a worm, they 
burst the silken shroud which envelopes them, and 
traverse the air in a form that is dazzling to the eyes. 
The Egyptians apparently referred to this inter- 
mediate state, and to the change which follows it, 
in the configuration of their mummies; for the most 
ancient are swathed and filleted, so exactly after the 
fashion of the Eruca, or Chrysalis, that the resem- 
blance could not be accidental. The sages of that 
country, who expressed all their notions by symbols, 
also signified the suppositious transmigration of the 
soul by the transformation of the insect ; and Grecian 
poets, improving on this idea, made use of the same 
symbol to designate its immortality. In like manner 
the botanist confesses, in the unfolding of the calyx 
which covers the gaudy head of the oriental poppy, 
an attractive emblem of the expanding of the human 
mind, as it emerges from a state of ignorance ; or in 
