INTRODUCTION. 5 



made against tliem some years ago, that tlieir " science 

 failed much in giving the origin, progress, migration, 

 mutual relation, struggle, decay, and final extinction of 

 species." 



Still, when we step out from the observation of fact 

 into the region of sj^eculation, we must feel less cer- 

 tain of our footing. Many difficulties beset us as soon 

 as we leave the "irrefragable direct geological evidence." 

 If we ask what has been the order of insect evolution, 

 and the channel through which one form rose from 

 another, the answer is obscure. 



In his Monograph of the Collembola and Thysanura, 

 Sir John Lubbock places before the reader in a succinct 

 form, considerations as to the probable parent stock of 

 Insecta, and he there so discusses the views of Fritz 

 Midler, Haeckel, Brauer, and Darwin, that it will be 

 right to touch but lightly upon it here. 



Some have felt considerable difficult in conceiving 

 evolutionary passages from the powerful gnawing jaws 

 of the Orthoptera or Coleoptera, into the weak suctorial 

 organs of the Hemiptera or Lepidoptera. In the last 

 family it will be remembered that the larvee are man- 

 dibulate, and the images are hau stellate. 



By adoption of Campodea (Thysanura) as an ances- 

 tral form, in which representative parts of jaws and 

 proboscis are present in the same insect. Sir J. Lubbock 

 thought much of this difficulty vanished. 



Fritz Midler elects the wingless Orthoptera, or 

 Blattidge, amongst existing insects, as most .nearly 

 approaching to the ancient form; and further, bethinks i 

 that the metamorphosis of the Coleoptera and Lepi- I 

 do^^tera was of later origin. The imperfect meta- ' 

 morphosis of the first insects, he thinks, is more like a 

 jDicture of an original mode of develoj)ment than the 

 perfect metamorphosis of beetles or moths. As to the 

 jjrobability of greater age in such an incomplete meta- 

 morphosis. Sir J. Lubbock quite agrees. 



Haeckel thought that the four mandibulate orders 

 preceded the four sucking orders in time, but that an 



