BIVALVES. 37 
rival the glowing colours of the papilionaceous tribes. 
In fine weather they congregate together and mount 
the billows, forming little fleets, with half their shells 
erected, to catch the breeze; the other, which con- 
tains the animal, remaining immerged below. When 
any foe appears, or a sudden gust of wind begins to 
ruffle the surface of the deep, the shells are instanta- 
neously shut, and the pigmy vessels disappear. 
The curious instincts of these interesting shell-fish 
most probably suggested the poetic chariots of the 
sea gods, who were fabled to ride triumphantly in 
shells drawn by tritons. Such was the car of Neptune, 
as we find in Virgil; and on a medal of Claudius: 
*¢ Hich on the waves his azure car he guides ; 
Its axles thunder, and the sea subsides. 
The monster whales before their master play, 
And choirs of tritons crowd the watery way: 
The martial powers in equal troops divide 
To right, and left; the gods his better side 
Enclose ; and, on the worst, the nymphs and nereids ride.” 
How sterile is the imagination of the poet when 
compared with the infinite variety of nature! The 
loftiest inspirations of his muse are frequently sug- 
gested by the humblest of her works; and from this 
imperishable source, the ancients derived their most 
poetic illustrations. Shell-fish are also represented 
on modern coins; and amongst some of the most 
