306 SUPPLEMENT 
tended in front, and it raises the other limbs, which are united 
by avery slender membrane, which it half opens, and it thus 
navigates as long as it perceives no danger: on any alarm, 
however, it sinks to the bottom, by its own proper weight, 
and by that of the shell, which it has filled with water, con- 
ceals itself, and escapes its enemy. As soon as the danger is 
past it reascends, and navigates afresh. It is from this 
operation that it has received its name. Thus lian has 
imitated Pliny in mentioning nothing concerning what was 
certain in Aristotle, and he cuts the difficulty by adding the 
epithet of znnate to the shell. 
Philo, a Greek writer, much more modern than those now 
cited, in his treatise on the nature of animals, and which is 
only a pure compilation, or rather an abridgment of Aristotle, 
has added nothing to what the latter has given us concerning 
the nautili. 
Belon, the most ancient of the naturalists, who wrote at the 
era of the revival of learning, appears to have been the first 
who considered the handsome partitioned shell which we re- 
ceive from India as another species of nautilus, and we shall 
presently see that it is the only one to which the name should 
remain. Nevertheless he has not referred it to the second 
species mentioned by Aristotle, but to a shell which is evi- 
dently but a large species of doliwm, and which, presenting 
the character of being very slender and light, might in truth 
belong to aswimming animal. It is unfortunate, however, that 
this is a true gasteropod, and that Aristotle has positively 
declared that the animal of his second species is a polypus or 
octopus. Belon adds nothing to the description of Aristotle’s 
first species but a bad figure, evidently designed from ima- 
gination. 
Rondelet manifestly copies Aristotle, and likewise gives a 
figure of the shell, which is supposed to be that of the first 
species; but the animal which he represents as belonging to 
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