148 CONCHOLOGIST’S COMPANION. 
or water. Thus, if the animal is stationary at the 
bottom of the sea, saturated with food, and having 
the syphon filled with water, we may conjecture from 
analogy, that in proportion as the food becomes 
digested and decomposed, detached gas will pass into 
the syphon, and gradually exclude the water, and so 
considerably diminish the specific gravity of the 
shell as to enable him to ascend readily to the 
surface. When, on the contrary, the Nautilus is 
inclined to descend, he lowers a small membrane 
which answers the purpose of a sail, contracts him- 
self within his boat, and filling the remaining cavity 
with water, immediately disappears. 
The facilities for thus escaping to his native 
dwelling in the fathomless abyss, are beautifully 
noticed in the following animated lines, which refer 
to the dangers of a sailor’s life. 
‘* The tender nautilus, who steers his prow, 
The sea-born sailor of this shell canoe ; 
The ocean Mab, the fairy of the sea, 
Seems far less fragile, and alas! more free! 
He, when the lightning-wing’d tornados sweep 
The surf, is sate, his port is in the deep, 
And triumphs o’er th’ armadas of mankind, 
Which shake the world, yet crumble in the wind.” 
This ingenious little sailor is frequently seen in 
fine weather, calmly riding on the billows with his 
