182 Mr. Swainson on the Natural Affinities 



spicuous in those groups wliere the series of affinities is so 

 perfect, and the change so gradual, as to set at defiance all 

 possibility of separating the minor divisions by absolute and 

 exclusive characters. 



Now, upon looking to the Lepidoptera, it does not require 

 any prejudice in favour of the foregoing principles, to dis- 

 cover five prominent groups of nearly equal magnitude, which 

 may be represented by the genera Papilio, Sphinx, Bombyx, 

 Geomctra, and Noctua of the Linnaean school. And further, 

 that while the two former are typical, the first represents the 

 greatest perfection, and the second contains not only types of 

 the other four divisions, but nearly so of all the subordinate 

 groups. 



In selecting the Lepidoptera Diurna of M. Latreille as a 

 subject for the present sketch, 1 shall avoid entering into de* 

 tails of those reasons which have induced me to abandon the 

 different arrangements proposed by others. Those of LinntEus 

 and Fabricius were confessedly artificial ; although the minor 

 groups of the latter deserve to have been better known, and 

 more generally adopted. The first attempt that I can dis- 

 cover towards a natural method, is that published by Geof- 

 froy in 1764*, which in all probability furnished the basis of 

 the classification adopted by the celebrated Latreille. Both, 

 in fact, are founded upon characters drawn from the larva and 

 pupa, and the partial or full development of the anterior feet 

 in the pefect insect. The former are so much diversified, as 

 to lead us to imagine that by attentively studying and judi- 

 ciously combining their forms, we may obtain some certain 

 clue to thread the labyrinth of affinities; or, at least, that we 

 shall make a nearer approach to the truth, than if we looked 

 only to the shape of the wings, or the nails of the tarsi. Yet 

 it must be confessed that difficulties are opposed to this line 

 of inquiry, which, in the present state of entomological know- 

 ledge, seem to me insurmountable. The larv^ of many con- 

 siderable groups inhabiting distant regions are to this day ut- 

 terly unknown : and even among those contained in the valuable 

 works of StoU and Abbot, there exists such a striking diver- 

 sity in the forms of larvae belonging to insects of the same na- 

 tural group, that no certam conclusions can, at present, be 

 made upon the subject. 



The pupa state likewise presents many remarkable varia- 

 tions. Yet as, upon the whole, it is confined to much fewer 

 forms, and these forms are better understood, there seems no 



* Was this borrowed from the illustrious DeGeer ? His invaluable "MS- 

 inoircs," now of very rare occurrence, I unfortunately do not possess. 



reason 



