56 [August. 



development of the vegetable kingdom, and as true flowers tlien began 

 to be abundant, it is likely that flower-feeding insects should have 

 simultaneously appeared. 



In the oldest strata (Lower Eocene) of this period, but few insects 

 have been detected ; but, in the Middle and Upper Eocene, and the 

 Lower, Middle and Upper Miocene, their remains have, in certain lo- 

 calities, been found in great numbers, and represent all the existing 

 Orders. 



As a rule, and possibly to some extent for the reasons before 

 given, the Goleoptera are better represented than any other Order ; 

 this is especially noticeable at Oeningen, in the Valley of the Rhine, 

 where, out of 844 species of fossil insects distributed among all the 

 existing Orders, 518 have been referred by Heer to this Oi'der. In 

 some localities, however, the Hymenoptera* are more numerous than 

 any other insects ; and in others the Dipteral are in a large majority. 



In every case the Lepidoptera is by far the rarest Order, and of 

 the butterflies only ten well authenticated species have been obtained 

 from all the localities in which fossil insects have been discovered. 



From the evidence at present obtained by Palseontological re- 

 searches, it appears that the Neuroptera is the oldest of the existing 

 Orders ; that it was followed by the Orthoptera, and that these two 

 Orders included almost all the insects of the Primary or Palaeozoic 

 period, towards the close of which the Coleoptera and Hemiptera fii-st 

 appeared. 



Early in the Secondary or Mesozoic period the two last named 

 Orders began to be abundant and widely distributed, and somewhat 

 later were followed by the Diptern and cei'tain families of the Hymen- 

 opt era. 



Towards the close of this period other families of the Jlymemoptera, 

 including the bees, appeared, and, about the same time, or early in the 

 Tertiary epoch, succeeded the Lepidoptera. X 



In the next paper I shall call attention to the correlation of fossil 

 insects with the fossilized remains of other animals, and with those of 

 the vegetable kingdom. 



Surbiton Hill : \st June, 1878. 



* From Radoboj in Croatia, 85 species are enumerated by Heer. 



t From Corent and Menat in Auvergne, 80 species ure enumerated by M. Oustalet. 



}An insent discovered in 1875 in the Belgian coal fields, was for some time believed by Dr. 

 Breyer and M. Preudhomme de Borre to belong to this Order • but Mr. McLachlan, after an ex- 

 amination of the fossil, decided that it was that of a Neuropterous insect belonging to the 

 Ephcmcrina. 



