80 THE CLASS OF INSECTS. 



158 ; those that are common to both hemispheres forming then 

 more than two-thirds of the whole number, while of the actual 

 Coleopterous fauna of Europe, according to the calculation of 

 M. Lacordaire, there is only one-third. The genera found to-day 

 in both parts of the world have then during the Tertiary epoch 

 played a more important part than is the case now ; hence 

 the knowledge of the character of the fauna is rendered more 

 difficult. We find at CEningen but a very small number (five) 

 of genera exclusively European ; seventeen are found to-da}' 

 in Europe, in Asia, and in Africa, but not in America. For the 

 most part they belong to the Mediterranean fauna (comprising 

 eight genera) and give to the insect-fauna of CEningen a strong 

 proportion of Mediterranean forms. In this fauna I only know 

 of one exclusively Asiatic genus ; two are peculiar to Africa ,. 

 and two others (Anoplites and Naupactus) are American. 



" There are now living, however, in Europe certain genera, 

 which, without being exclusively American, since they are found 

 in Asia and in Africa, belong more peculiarly to America ; such 

 are Belostomum, Hypselonotus, Diplonyclius, Evagoms, Sten- 

 opoda, Plecia, Caryborus, and Dineutes. . . . The genera peculiar 

 to our fauna of Tertiary insects amount to forty-four, of which 

 twenty-one belong to the Coleoptera ; among the Orthoptera 

 there is one, and six Hymenoptera, six Diptera, and eleven 

 Hemiptera. They comprise 140 species." (Heer.) 



An apparently still richer locality for Tertiary insects has- 

 been discovered by Professor Denton west of the Rocky Moun- 

 tains, near the junction of the White and Green Rivers, Colo- 

 rado. According to Mr. Scudder "between sixty and seventy 

 species of insects were brought home, representing nearly all 

 the different suborders ; about two-thirds of the species were 

 Flies, some of them the perfect insect, others the maggot-like 

 larvae, but, in no instance, did both imago and larva of the 

 same insect occur. The greater part of the beetles were quite 

 small ; there were three or four kinds of Homoptera (allied to 

 the tree-hoppers), Ants of two different genera, and a poorly 

 preserved Moth. Perhaps a minute Thrips, belonging to a 

 group which has never been found fossil in any part of the 

 world, is of the greatest interest." 



He thus sums up what is known of American fossil insects. 



