470 NATURAL HISTORY OV AFRICA. 
Several species of sepia, or cuttle-fish, occur on 
the coasts of this continent. Some of them appear 
to be much larger than any of those met with on 
our coasts , and, if we can credit the accounts of 
travellers, some of the African species attain a co- 
lossal size. \ 
The animals of the Argonaut tribe are nearly al- 
lied to the cuttle-fish. The famous nautilus of the 
ancients (the Argonauta argo, Lin.) which is sup- 
posed, in the early ages of the world, to have fur- 
nished the original idea of navigation, is found in 
the African seas, as in the neighbourhood of the 
Cape of Good Hope. When it means to sail, this 
animal discharges a quantity of water from its shell, 
by which means it is rendered lighter than the 
surrounding medium, and of course rises to the 
Surface. Here it extends two of its tentacula up- 
wards. These are each furnished at their extremi- 
ty with an oval membrane, which serves as a sail. 
The other six arms, or tentaculae, hang over the 
sides of the shell, and are alleged to supply the 
place of oars and rudder. In some places, when 
the sea is not agitated by winds, great numbers of 
these curious animals may occasionally be seen sail- 
ing about in this manner ; but as soon as the storm 
arises, or any thing disturbs them, they retract 
their tentacula, take in as much water as renders 
them heavier than that in which they swim, and 
sink to the bottom. 
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