PREFACE TO THE FIRST EDITION. XXI 



forms of shells belong, and to arrange the latter from that con- 

 sideration; but as to the ulterior divisions of those shells whose 

 animals resemble each other, I have examined them only so 

 far as to enable me to describe those admitted by Messrs de 

 Lamarck and de Montfort; even the small number of genera or 

 subgenera which are properly mine, are derived from observa- 

 tions on the animals. In citing examples I have confined my- 

 self to a certain number of the species of Martini, Chemnitz, 

 Lister, and that only (the volume of M. de Lamarck, which 

 is to contain these matters, not being published), because I 

 was compelled to fix the attention of the reader on specific 

 objects. In the selection and determining of these species 

 however I lay no claim to the same critical accuracy I have 

 employed for the Vertebrated animals and the naked Mol- 

 lusca. 



The excellent observations of Messrs Savigny, Lesueur, 

 and Desmarest on the compound Ascidia, approximate the 

 latter family of the Mollusca to certain orders of Zoophytes 

 a curious relation, and an additional proof of the impractica- 

 bility of arranging animals on one single line. 



The Annul^ta (the establishing of which order, although 

 not the name, belongs de facto to me) have I think been ex- 

 tricated from the confusion in which they had hitherto been 

 involved among the Mollusca, the Testacea, and the Zoophy- 

 tes, and placed in their natural order even their genera have 

 been elucidated only by my observations on them, published 

 in the '^ Dictionnaire des Sciences Naturelles," and elsewhere. 



I can say nothing relative to the three classes contained in 

 the third volume. M. Latreille, who, with the exception of 

 some anatomical details, founded on my own observations and 

 those of M. Randohr, added to his text, is its sole author, 

 will spare me that trouble. 



As to the Zoophytes, which terminate the animal kingdom, 

 I have availed myself, for the Echinodermata, of the late work 

 of M. de Lamarck, and for the Intestinal Worms, of that of 

 M. Rudolphi, entitled Entozoa; but I have anatomized ail 

 the genera, some of which have been determined by me only. 



