80 THE CLASS or INSECTS. 



158 ; those that are common to both hemispheres forming then 

 more than two-thirds of the whole number, wliile 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 ffiningen 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 {AnopUtes 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, Dix)lonychus, Evagorus, Sten- 

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

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

 twent3^-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 w^ere 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. 



