334 INSECTA 



found at many horizons in the Mesozoic and Cainozoic 

 formations ; in England they are not uncommon in the 

 Lias, the Stonesfield Slate, the Purbeck, the Wealden, 

 and the Bembridge Beds. They are well represented in 

 the Solenhofen Limestone (Upper Jurassic) of Bavaria, in 

 the Miocene of Oeningen in Switzerland, and of Florissant 

 in Colorado, and in the amber from the Oligocene Beds of 

 Prussia. 



The Insects found in the Palaeozoic formations appear 

 to be more generalised than the later forms, and the 

 majority are referred by Handlirsch to Orders distinct 

 from those found in Mesozoic and later periods. Only 

 one Order, the Orthoptera, seems to have survived from 

 Palaeozoic to later times. One of the extinct Orders — the 

 PalaeOdictyoptera, is regarded as the ancestral stock from 

 which the other Palaeozoic Orders originated, and the 

 latter are considered to be connecting links between the 

 Palaeodictyoptera and modern insect groups. Brongniart, 

 however, believes that the Carboniferous insects can all be 

 placed in the Orders adopted for existing forms, but that 

 in Palaeozoic times the Orders were less sharply separated 

 than at the present day. 



The Insecta include an enormous number of forms, 

 and the specimens found fossil are often imperfectly pre- 

 served, so that nothing more than a brief sketch of the 

 distribution of the chief groups can be attempted here. 



ORDER I. APTERA 



The fossil examples of this Order (which contains 

 small wingless insects) are found mainly in amber from 

 the Oligocene of Prussia, and include several species of 

 Lepisma, the silver-fish. 



