190 LAMARCK, HIS LIFE AND WORK 
tures of the year 1799 he established the class of 
Crustacea, and adds that “although this class is es- 
sentially distinct, it was not until six or seven years 
after that some naturalists consented to adopt it.” 
The year following, or in his course of 1800, he sepa- 
rated from the insects the class of Arachnida, as “ easy 
and necessary to be distinguished.” But in 1809 he 
says that this class “is not yet admitted into any other 
work than my own.”* As to the class of Annelides, 
he remarks: ‘ Cuvier having discovered the existence 
of arterial and venous vessels in different animals 
which have been confounded under the name of 
worms (Vers) with other animals very differently 
organized, I immediately employed the consideration 
of this new fact in rendering my classification more 
perfect, and in my course of the year 10 (1802) I es- 
tablished the class of Annelides, a class which I have 
placed after the molluscs and before the crustaceans, 
as their known organization requires.”’ He first es- 
tablished this class in his Recherches sur les corps 
vivans (1802), but it was several years before it was 
adopted by naturalists. 
The next work in which Lamarck deals with the 
classification of the invertebrates is his Dzscours 
ad’ ouverture dau Cours des Animaux sans Vertcbres, 
published in 1806. 
* In his Wistotre des Progrés des Sciences naturelles Cuvier takes 
to himself part of the credit of founding the class Crustacea, stat- 
ing that Aristotle had already placed them in a class by themselves, 
and adding, ‘* AZALI. Cuvier et de Lamarck les en ont distingués par des 
caractéres de premier ordre tirés de leur circulation.” Undoubtedly 
Cuvier described the circulation, but it was Lamarck who actually 
realized the taxonomic importance of this feature and placed them 
in a distinct class. 
