CONSIDERATIONS. 279 



Supposing we had studied with equal care the organization 

 of every animal, and had then placed together the species, 

 genera, and families, which have the greatest affinities, we 

 should easily have recognized their true connexions. 



This mode of proceeding would have shown that the series 

 of animals does not form a simple and uniformly decreasing 

 scale, but that each division presents a peculiar mode of organi- 

 zation ; that from the point in which the organization is most 

 perfect in each of these great divisions, the animals decrease in 

 perfection of structure towards the other divisions ; and that 

 the same occurs in most of the subdivisions. 



Hence it results that, in any division, the species which 

 offers the most elevated organization may be more perfect than 

 that which is placed at the confines of an anterior division. 

 An insect is more perfect than a Lampreda, though this last 

 is nearer to man. 



In arranging animals according to the relationship of all 

 their organs, we find, with M. Lamarck, that certain families 

 conduct, at the same time, to two or three others, which gives 

 the whole scale a ramose disposition. 



Leaving the Annelida by Leodice, we enter the Myriapoda 

 by Polyxenus, from which class we pass, on one hand, to 

 the Crustacea by Armadillo — on the other, to the insects by 

 Lepisma. 



From the Thysanura we are conducted to the Coleopiera 

 by Forficula, thence to the Brachelytra, leading to the Silphce 

 and neighbouring genera, which precede the Carabi ; from 

 these last we proceed to the other Coleopiera, which hence- 

 forth are not connected with any other division. Forficula 

 conducts also to the Orthoptera, of which the first genus is 

 Thrips,^ so that this latter oi'der, instead of following the 

 Coleopiera, forms a branch placed beside them. From the 

 Orthoptera we arrive successively, on the one hand, at the ISeu- 

 roptera, Hymenoptera, Diptera, and Aptera ( Aphaniptera ) ; 

 on the other, at the Hemiptera and Lepidoptera ; and this 

 last order terminates the third division of the class Insecta. 



The isopod Crustacea, after having formed a lateral branch. 



a Tkrips is mostly placed with the Hemiptera ; but as it has trophi resembling 

 those of the Mandibulata, and particularly long curved mandibles, it must belong 

 to the Orthoptera, at the head of which order is its appropriate station. 



