RESULTS OF PAL^ONTOLOGICAL RESEARCH 39 



Our illustration shows such a transitional group from 

 the Palaeozoic system which Handlirsch regards as 

 the ancestral form of the Scorpion flies, Phryganidae, 

 Flies, and Butterflies. 



In the Mesozoic system the primary form is no 

 longer found and the 

 transitional forms are 

 scarcer. ' Nearly all the 

 insects found in these 

 formations can be allo- 

 cated without difficulty 

 to the now existent 

 orders, although they 

 differ sufficiently from 

 many of the present forms 

 to be considered separate 

 families or at least genera. ' 



There appear true 

 Locusts, Grasshoppers, 

 Stick Insects, Beetles, 

 Phryganidee, Dragon- 

 flies, Hemiptera, Butter- 

 flies, Bugs, etc., so that at the end of the Jura 

 period (Figs. 7-9) all the chief groups of the insect 

 world are existent with the exception of the Earwigs, 

 Termites, Woodlice, Field-cricket, and the true Lice 

 (infesting warm-blooded animals), Fur-eaters and 

 Fleas (Parasites). Within the orders, however, there 

 are still lacking many now widely extended families, 

 such as Wasps, Ants, Bees, true Flies, Gall-wasps, etc. 



FlG. 6. A TRANSITIONAL FORM FROM 



THE CARBONIFEROUS SYSTEM. (After 

 Handlirsch.) 



