42 OBSERVATIONS ON THE ANIMALS 
animal life; and in the latter by very great numbers of Terebratulz 
and Brachiopodous animals, which must also have required a very 
large supply of food in those ancient seas. 
There is one very interesting fact, with regard to the genus Nau- 
tilus, which must not be passed over ; we mean their universal distri- 
bution throughout marine deposits, from almost the first appearance 
of animal life to our own times. There are, indeed, species of Nau- 
tilus peculiar to every formation, from the transition limestone to the 
chalk ; others entirely confined to the tertiary deposits; and others, 
again, as the N. Pompilius and N. umbilicatus, found living in the 
waters of the ocean. When it is remembered that this long continu- 
ance of a genus is almost without parallel in the history of animal 
life, and also that it occurs in a class remarkable for high organiza- 
tion, the importance of the subject will be in some measure seen, and 
we shall be justified in dwelling so long upon this part of it. In 
fact, if it were not for our knowledge of the recent Nautilus and its 
habits, almost the whole subject of fossil multilocular shells would 
be entirely beyond our reach. What is now certainty would be mere 
matter of conjecture ; and notwithstanding the vast number, both of 
species and individuals, we should scarcely be able to make out, with 
any degree of probability, to what kind of animals they once belong- 
ed, whether they were zoophagous or phytiphagous, or, indeed, any 
one point in their whole history. The Nautilus is the guide in all 
our researches, and it leads us to a knowledge of the natural history 
of many races now extinct, by those principles of analogy which, 
when properly and carefully employed, are as certain as they are use- 
ful in determining the habits of beings now no longer in existence. 
Next in order to the genus Nautilus, we have mentioned one which 
will be new to most of our readers—the Endosiphonites, occurring 
earlier in geological position than Nautilus, but apparently extremely 
limited in the extent of its range. In this genus the siphuncle is on 
the inner margin of the shell, and the whorls of the spiral, although 
they all touch each other, are not found to wrap over, or, as it is 
usually called, envelope, the inner ones. The walls or septa of the 
chambers are also, on the whole, more generally complicated in their 
form than perfectly simple or cup-shaped ; and in all these points 
there will be observed a departure from the generic character of the 
Nautilus. This genus was first separated by Count Minster, in 
consequence of certain species observed in the transition limestone of 
the Fichtelgebirge (a mountain in the south of Germany, not far 
from Nuremberg), and was called by him Clymenia, which, as it had 
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