heir peculiar colors, and
their nacre.

"Other fossils have undergone such an alteration that not only have
they lost their animal portion, but their substance has been changed
into a silicious matter. I give to this second kind of fossil the
name of _silicious fossils_, and examples of this kind are the
different oysters ('des ostracites'), many terebratulae ('des
terebratulites'), trigoniae, ammonites, echinites, encrinites, etc.

"The fossils of which I have just spoken are in part buried in the
earth, and others lie scattered over its surface. They occur in all
the exposed parts of our globe, in the middle even of the largest
continents, and, what is very remarkable, they occur on mountains up
to very considerable altitudes. In many places the fossils buried in
the earth form banks extending several leagues in length."[82]

Conchologists, he says, did not care to collect or study fossil shells,
because they had lost their lustre, colors, and beauty, and they were
rejected from collections on this account as "dead" and uninteresting.
"But," he adds, "since attention has been drawn to the fact that these
fossils are extremely valuable _monuments_ for the study of the
revolutions which have taken place in different regions of the earth,
and of the changes which the beings living there have themselves
successively undergone (in my lectures I have always insisted on these
considerations), consequently the search for and study of fossils have
excited special interest, and are now the objects of the greatest
interest to naturalists."

Lamarck then combats the views of several naturalists, undoubtedly
referring to Cuvier, that the fossils are extinct species, and that the
earth has passed through a general catastrophe (_un bouleversement
universel_) with the result that a multitude of species of animals and
plants were consequently absolutely lost or destroyed, and remarks in
the following telling and somewhat derisive language:

"A universal catastrophe (_bouleversement_) which necessarily
regulates nothing, mixes up and disperses everything, is a very
convenient way to solve the problem for those naturalists who wish
to explain everything, and who do not take the trouble to observe
and investigate the course followed by nature as respects its
production and everything which constitutes its domain. I have
already elsewhere said what should be thought of this so-called
univers