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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 Discours 

 d'ouverture du Cours des Animaux sans Vertebres, 

 published in 1806. 



* In his Histoire des Progrh des Sciences naturelles Cuvier takes 

 to Iiimself part of the credit of founding the class Crustacea, stat- 

 ing that Aristotle had already placed them in a class by themselves, 

 and adding;, " MM. Cuvier et de Laviarck les en oni distingu^s par des 

 caracth-es de premier ordre iirh 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. 



