38 



THE THEORY OF EVOLUTION 



of the wings was well developed ; the antennae consisted 

 of numerous segments; the rear segments of the body 

 frequently bore gill-like appendages. 



By the appearance of their masticating and well- 

 developed jaws they were carnivorous. Their larvae 

 lived probably in water like the present Ephemeridae. 

 The body was equally segmented (homonomous). 



The whole of the primary insects form together the 



one order of Palaeo- 



i / 



dictyoptera, but this 

 consisted of twenty-two 

 families and 115 species. 

 The numerous orders 

 of the insects of the 

 present day are still 

 absent. In the upper 

 strata of the Palaeozoic 

 period insects appear 

 which ' undoubtedly 

 present a definite ten- 

 dency towards the modern insect orders/ l Handlirsch 

 considers them as ' transitional groups between the 

 primary groups and those to-day existent, the Ortho- 

 ptera, Woodlice, Dragon-flies, Ephemeridae, Hemiptera, 

 etc/ In the old terrestrial formations, however, we 

 find already true Woodlice, Ephemeridae, and Locusts : 

 ' the Palaeozoic fauna is therefore totally different 

 from the modern and much more uniform ' 2 (Fig. 6). 



FIG. 5. RECONSTRUCTION OF THE PRIMARY 

 INSECT (reduced). (After Handlirsch.) 



1 Die Umschau, p. 589. 



Ibid. 



