XIV PREFACE TO THE FIRST EDITION. 



the Annukta, the Radiata, and many of the Insects and Crus- 

 tacea, is equally extensive. I have not deemed it necess- 

 ary to publish it with the same detail ; but all my prepara- 

 tions are exposed in the Cabinet of Comparative Anatomy in 

 the Jardin du Roi, and will serve hereafter for my Treatise 

 on Anatomy. 



Another work of considerable labour, but wliose proofs 

 cannot be made so authentic^ is the critical examination of 

 species. I examined and verified all the figures adduced by 

 authors, and as often as possible referred each to its true spe- 

 cies, before making a choice of those I have pointed out ; it is 

 from this verification alone, and never from the classification 

 of preceding methodists, that I have referred to my sub- 

 genera the species that belong to them. Such is the reason, 

 why no astonishment should be experienced on finding that 

 such or such a genus of Gmelin is now divided and distributed 

 even in different classes and divisions; that numerous nominal 

 species are reduced to a single one, and that vulgar names are 

 very differently applied. 



There is not a single one of these changes that I am not 

 prepared to justify, or of which the reader himself may not 

 obtain the proof by recurring to the sources I have indicated. 



In order to diminish his trouble, I have been careful to se- 

 lect for each class a principal author, generally the richest iu 

 good original figures, and I quote secondary works only in 

 those cases in which the former are silent, or where it was 

 useful to establish some comparison, for the sake of confirm- 

 ing synonymes. 



My subject could have been made to fill many volumes, 

 but I considered it my duty to condense it, by imagining 

 abridged means of publication. I have obtained these by gra- 

 duated generalities ; by never repeating for a species what 

 could be said of a whole subgenus, nor lor a genus what might 

 be applied to an entire order, and so on, we arrive at the 

 greatest possible economy of words. To this my endeavours 

 have been, above all, particularly directed, inasinuch as this 

 was the principal end of my work. It may be observed, 



