1798 Insects. 



suggesting that there may be a difference between the two : thus we 

 are told of the pupa of a winged insect producing young through its 

 mouth. The reason for my not embracing this view of the subject, is 

 that three conclusions are thus begged ; first, that in Stylops, the 

 pupa produces living young ; secondly, that the head is filled with 

 these living young ; and thirdly, that the living young escape 

 through the mouth : both positive observation and analogical reason- 

 ing lead to the converse of these conclusions, and therefore the en- 

 quiry is not advanced by adopting them. I do not say they are un- 

 true, but I maintain that in the first place, they are unproved ; in 

 the second place they are improbable ; in the third place, they are 

 unnecessary. 



§ 2. Comparative Economy and Metamorphosis of Stylops. 



The penultimate state, or that immediately preceding the last ecdy- 

 sis, is that on which the metamorphotic method is founded, this state 

 is called the pupa, and its differences are ranged under three heads. 

 First, it is called isomorphous, when it resembles the imago in struc- 

 ture, in activity, in eating, and all respects, except in the perfect de- 

 velopment of wings. Secondly, it is called necromorphous, when it 

 resembles the imago in all respects, except in being perfectly quies- 

 cent, as though dead. Thirdly, it is amorphous, when it has no 

 similarity to the imago, either in figure or activity.* The penulti- 

 mate or pupa state of Stylops is necromorphous. The necro- 

 morphous classes are Hymenoptera and Coleoptera. The pupa 

 of Stylops has no character by which it can be distinguished 

 from the usual pupae of these two classes. I know of no in- 

 sect in the isomorphous or amorphous classes that presents any avail- 

 able similarity to Stylops in its pupa state. We have, therefore, no 

 choice but to regard Stylops as belonging to the metamorphotic class 

 Necromorpha. It cannot be said to have an affinity with this class : 

 such an expression would not convey the truth ; it possesses all the 

 characters of the class in their typical or normal state. 



The metamorphotic or double class Necromorpha exactly corres- 

 ponds with the two alary or single classes Hymenoptera and Coleop- 

 tera : as the pupa of these is exactly similar, it becomes necessary to 



* See a more detailed account of the metamorphotic method in the ' Familiar 

 Introduction to the History of Insects,' pasjc 73. 



