vertebrates is his _Discours d'ouverture du Cours des Animaux sans
Vertebres_, published in 1806.

On page 70 he speaks of the animal chain or series, from the monad to
man, ascending from the most simple to the most complex. The monad is
one of his _Polypes amorphs_, and he says that it is the most simple
animal form, the most like the original germ (_ebauche_) from which
living bodies have descended. From the monad nature passes to the
Volvox, Proteus (Amoeba), and Vibrio. From them are derived the
_Polypes rotiferes_ and other "Radiaires," and then the Vers,
Arachnides, and Crustacea. On page 77 a tabular view is presented, as
follows:

1. _Les Mollusques._
2. _Les Cirrhipedes._
3. _Les Annelides._
4. _Les Crustaces._
5. _Les Arachnides._
6. _Les Insectes._
7. _Les Vers._
8. _Les Radiaires._
9. _Les Polypes._

It will be seen that at this date two additional classes are proposed
and defined--_i.e._, the Annelides and the Cirrhipedes, though the class
of Annelida was first privately characterized in his lectures for 1802.

The elimination of the barnacles or Cirrhipedes from the molluscs was a
decided step in advance, and was a proof of the acute observation and
sound judgment of Lamarck. He says that this class is still very
imperfectly known and its position doubtful, and adds: "The Cirrhipedes
have up to the present time been placed among the molluscs, but
although certain of them closely approach them in some respects, they
have a special character which compels us to separate them. In short, in
the genera best known the feet of these animals are distinctly
articulated and even crustaceous (_crustaces_)." He does not refer to
the nervous system, but this is done in his next work. It will be
remembered that Cuvier overlooked this feature of the jointed limbs, and
also the crustaceous-like nervous system of the barnacles, and allowed
them to remain among the molluscs, notwithstanding the decisive step
taken by Lamarck. It was not until many years after (1830) that Thompson
proved by their life-history that barnacles are true crustacea.

In the _Philosophie zoologique_ the ten classes of the invertebrates are
arranged in the following order:

_Les Mollusques._
_Les Cirrhipedes._
_Les Annelides._
_Les Crustaces._
_Les Arachnides._
_Les Insectes._
_Les Vers._
_Les Radiaires._
_Les Polypes._
_Les Infusoires._

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