Insects of Past Ages 355 



already developed in the early Jurassic (Lias) period. 

 In rocks of Jurassic age also remains of Dragonflies, 

 both imagos and larva% referable to the existing 

 families, are fairly abundant. Going back again to the 

 Carboniferous rocks of France, gigantic insects have 

 been discovered with a general likeness to living 

 dragonflies, but with less specialised thoracic seg- 

 ments and simpler wing-neuration (204). These may 

 perhaps be regarded as a link between the recent 

 Odonata and their far-off Platypteroid ancestors. 

 Some fragments of wings from Devonian rocks have 

 been also referred to the precursors of Dragonflies. 



A fossil insect of Devonian age {Engereon B'dckifigi^ 

 furnishes an interesting link in the history of the 

 Hemiptera. Its jaws appear to have been almost 

 typically hemipterous in structure, but its wings 

 were like those of the primitive orthopteroid insects 

 just mentioned (203). It points to orthopteroid or 

 platypteroid forms as the ancestors of the Hemiptera, 

 while it seems to indicate clearly that the hemipterous 

 mouth had been developed before the modifications in 

 wing-structure which characterise the existing sub- 

 orders of Hemiptera had appeared. In the Carboni- 

 ferous rocks of North America a wing {Phthanocoris 

 Occident alis) has been found which shows a decided 

 approach to the fore-wing of the recent Heteroptera, 

 presenting a large firm corium, a narrow clavus, and 

 a terminal membrane (203). Coming into the 

 Secondary epoch we find that the existing families of 

 Fulgorids and Aphid^ were already existing in the 

 Oolite, and Cicadidae as early as the Lias. Of the 

 Heteroptera the Coreidae and Lygseidae can be traced 

 back to the Lias and the Nepidee and Reduviida- to 

 the Oolite ; the other families are only certainly repre- 

 sented in Tertiary rocks, where the few known fosil 

 Thysanoptera also occur (203). 



