MEMOIR OF LAMARCK. 
51 
very brief, are in general highly satisfactory. These 
circumstances have rendered this work the most 
valuable system that has ever appeared of the in- 
vertebrate animals ; and it has formed the guide to 
most authors who have since written on the sub- 
ject*. 
The phrase invertebrate animals originated with 
Lamarck, and it expresses, as Cuvier remarks, per- 
haps the only circumstances in their organization 
which is common to them all. They were pre- 
viously known as white-blooded animals, a designa- 
tion which was soon shown to be improper, by the 
discovery that an entire class (the annelides ) pos- 
sesses red blood. The system of Linnams and Bru- 
guiere formed the basis of his course when he first 
began to lecture on the subject; he subsequently 
adopted a new classification, founded on their 
anatomy, which had been published in 1795. This 
he afterwards modified in various ways, as new dis- 
coveries were made, and as new relations sucgested 
themselves to him. In his system of invertebrata, 
forming an octavo volume, published in 1810, he 
adopted the class of Crustacea, and created that of 
arachnites, a step which he judged necessary, in 
consequence of some new information that had been 
communicated to him on the heart and pulmonary 
sacs of spiders. In a previous work he had ad- 
mitted the annelides to the rank of a separate class, 
* The most recent and probably the best edition of the 
Animaux sans Vertebres, is in eight volumes octavo, augmented 
with notes by >1. M. Deshages and Milne Edwards. 
