THE ATLANTIC OCEAN. 221 
being accomplished, the sand is again scraped back 
over the eggs, and the surface made smooth as before. 
The sun soon hatches the eggs, and the little Turtles 
crawling forth from the sand, betake themselves to 
the sea. The usefulness of this animal as an article 
of luxurious food is well known; but its real value 
can only be appreciated, when we view it as afford- 
ing an immediate relief from the horrors of scurvy, 
which, arising from the constant use of salted pro- 
visions, has often proved so terrible a scourge in 
long voyages. There is a peculiarity in the struc- 
ture of the heart of this and kindred animals, which 
is worthy of notice. In man and other warm-blooded 
animals, the blood is brought by the veins to the 
heart, and poured into a chamber called the right 
auricle; a communication exists between this and 
a second chamber, called the right ventricle; from 
the latter the blood is forced through a large ar- 
tery to the lungs, to be renewed by exposure to the 
air; from the lungs it is sent through veins to a 
third chamber of the heart, called the lft auricle, 
and thence into a fourth, called the d/t ventricle, 
from which the great artery, called the aorta, carries 
it again into the whole body. Thus, no particle of 
the blood can be conveyed again into the system 
without having passed through the lungs; but in the 
Turtle the case is different. All the four cham- 
bers of the heart are present, but there is a commu- 
nication open between the left and right ventricles ; 
and the aorta and pulmonary artery both originate 
from the right ventricle. In consequence, a part 
only of the blood is sent thence to the lungs, which, 
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