hi INTRODUCTION 



from the molluscs, and combined them with his class of 

 echinoderms to form the class of radiarians.^ 



In 1799 Lamarck removed the crustaceans from among 

 the insects, and erected them into a separate class. This 

 innovation was not recognised for some years. In the follow- 

 ing year he performed a still more remarkable achievement, 

 in separating the arachnids from the insects, and conferring 

 class-distinction on them also. Up to the date of publica- 

 tion of the Philosophie Zoologique, this class had not been 

 admitted in the work of any other naturalist. Lamarck 

 further reduced the old class of worms by separating from 

 them the new class which he called annelids. This important 

 innovation likewise took some years before it received general 

 recognition. Lastly, he established the class of infusorians, 

 as distinct from his previous class of polyps. Lamarck's 

 infusorians correspond of course to what we now call Proto- 

 zoa ; but there was a good deal of confusion as to what 

 animals were infusorians and what polyps, owing to deficiency 

 of observation. Minor improvements in classification were 

 also numerous. He removed the cirrhipedes, for instance, 

 from the neighbourhood of annelids and molluscs : he 

 recognised the gastropod affinities of pteropods, etc., etc. 



In the present work, Lamarck gives a list of all genera 

 known at his time, arranged in their proper order and 

 classification. The names of the genera are not given in 

 Latin, but in French ; and for a large number of them 

 Lamarck himself appears to have invented popular names, 

 based on the scientific names. It has therefore been a 

 matter of considerable difficulty to ascertain precisely to 

 what animals he is alluding in each case. The difficulty is- 

 still further increased by the fact that many of these genera 

 are no longer recognised : a large proportion of them in 

 fact are far more allied to what we should call families than 



^ Professor Packard, who some years ago published in America extremely literal 

 translations of certain parts of Lamarck's work, translates radiaires as radiata. This 

 is somewhat ambiguous ; for Cuvier's class of radiata is far wider than Lamarck's 

 class of radiaires, and includes infusorians, polyps and many worms. The correct 

 translation is radiarian. I preserve the popular style. 



