160 Mr. J. O. Westwood on the Oriental Species 



such theories has constantly been attended with new suggestions, 

 often highly original, interesting, and valuable ; and thus no one 

 can rise from a careful study of the theoretical portions of the works 

 of MacLeay, Vigors^, Horsfield, Swainson, or Newman, without 

 being struck with the many new ideas which these writers have 

 formed on the natural distribution and arrangement of the various 

 objects of nature on which they have exercised their talents and 

 ingenuity. That one and all of them should have occasionally 

 bent or even sacrificed nature to theory is no more to be wondered 

 at than the discovery of the true system of nature itself would 

 have been with the few genuine materials we at present possess, 

 accumulated as they have been within so few years. 



Let us see, for instance, what are the chief points in a Lepidop- 

 terous insect which appear likely to be of importance in enabling 

 us to judge of its natural relation and place in the system of 

 nature. I do not here allude to its internal anatomy, although 

 no one can doubt that this is even of higher importance than its 

 external structure. 



Structure of the egg and its peculiarities ; external form of the 

 larva at its different periods of growth ; structure of its mouth, 

 spiracles, legs, prolegs, caudal appendages, &c. ; external form 

 and other peculiarities of the chrysalis, its mode of suspension or 

 situation in a cocoon or otherwise ; external structure of the per- 

 fect insect, including its antennae, their form and number of 

 joints, spiral tongue and palpi ; eyes ; legs, with their tarsi and 

 ungues ; form and position of the wings ; arrangement of wing 

 veins ; abdomen and abdominal appendages in the opposite sexes, 

 and other sexual differences; natural habits and economy; time of 

 flight, geographical distribution, size, colour, and markings. 



Now how many Lepidopterous insects have been studied in 

 such a manner as will clearly enable us to form an opinion on all 

 these various peculiarities and points of structure ? Lyonnet spent 

 a life in examining the goat moth, Cossus I'tgniperda, in its various 

 states, but it is only the larval portion of his inquiry which 

 he had time satisfactorily to complete. To affirm that any 

 one of these peculiarities or characters is of superior importance 

 to the rest, as affording a key to a natural system of Lepidoptera, until 

 such a thorough investigation has been made of one or more species 

 in each of the principal groups of Lepidopterous insects, seems to 

 me to be liable to lead to error, not only from positive want of 

 knowledge of facts, but also from a want of recognition of that 

 principle which seems to pervade nature, namely, that characters 

 which in one group appear to be of primary importance, become 



