PREFACE. V 



manner in wliicli they arc reticulated. It is in fact a union of the 

 system of Fabricius with that of Linnaeus perfected. 



The divisions made by our savant in his first order, that of the 

 Gnathaptera, are nearly similar to those I had established in a Memoir 

 presented to the Societe Philomatique, April, 1795, and in my Precis 

 des Caraderes Generiques des Insectes*. 



M. de Lamarck, whose name is so dear to the friends of natural 

 science, has ably profited by these various labours. His systematic 

 arrangement of the Linnsean Aptera appears to us to be that which 

 approaches nearest to the natural order, and, with some modifications 

 of which Ave are about to speak, is the one we have followed. 



I divide the Insects of Linnaeus, with him, into three classes : the 

 Crustacea, Arachnides and Insecta; but in the essential characters 

 which I assign to them, I abstract all the changes experienced by 

 these animals, prior to their adult state. This consideration, although 

 natural, and previously employed by De Geer in his arrangement of 

 the Aptera, is not classical, inasmuch as it supposes the observation 

 of the animal in its different ages; it is, besides, liable to many 

 exceptions f . 



The situation and form of the branchiae, the manner in which the 

 head is united to the thorax, and the organs of manducation, have 

 furnished me the means of establishing seven orders in the class of 

 the Crustacea, all of which appear to me to be natural. I terminate 

 it, with M. de Lamarck, by the Branchiopoda, which are a sort of 

 Crustacea Arachnides. 



In the following class, that of the Arachnides, I only include the 

 species which in the system of Lamarck compose the order of his 

 Arachnides palpistes, or those which have no antennae. Beyond 

 this, the organization of these animals, external as well as internal, 

 furnishes us with a simple and rigorous rule that is susceptible of a 

 general application. 



* I there divided the Aptera of Linnseus into seven orders: 1. The Suctoria. 

 2. The Thysanoura. 3. The Parasita. 4. The Acephala (Arachnides pal- 

 pistes, Lam.) 5. The Entomostraca. 6. The Crustacea. 7. The Myrxa- 



PODA. 



t These considerations, however, have not been overlooked, and I have used them 

 advantageously in grouping families, and arranging them in a natural order, as may 

 be seen by a reference to the historical sketches which precede the exposition of 

 those families. I have even been employed on a work respecting the metamorphosis 

 of Insects in general, which has not yet been published (see article '^ Insectes,^' Nouv. 

 Diet. d'Hist. Nat. Ed. 2d), but which I have long been maturing, and which I have 

 communicated to my friends : I have made use of it in the course of my general 

 remarks. 



