HEMIPTERA— nOMOPTEEA. 239 



multitude of minor points to show distinct tropical relations, and it therefore 

 becomes of peculiar interest to learn the numerical relation herein of the 

 Homoptera to the Heteroptera. Now here, much as in the Oligocciue of 

 Europe, we find the Homoptera claiming- 40 per cent of the whole hemip- 

 terous fauna. The significance of these tig-ures can hardly be doubted. 



The number of Tertiary Hemiptera of the whole world is now to be 

 reckoned at 5C9, of which 355 are Heteroptera and 214 Homoptera. The 

 abundance of Hemiptera in our Western Tertiaries may perhaps fairly be 

 pictured when we remember that Heer in his first elaboration of those found 

 in the rocks of Europe enumerated 133, and that in the present work, the 

 first elaboration of those of America, the number is almost exactly double, 

 2ii5. 



In studying- this group I have been greatly aided by many kind favors 

 from my friends, Mr. P. R. Uhler, of Baltimore, and Mr. E. P. Van Duzee, 

 of Buffalo. 



Order HOIVLOPTER^ LatreiHe. 



The variety of forms referable to the families of Homoptera that have 

 been found in the American rocks is not a little surprising, and it includes 

 some remarkable forms. All the families are represented excepting- the 

 Stridulantia, and this exception is the more noticeable because the presence 

 of this family has been signalized in several instances in the European Ter- 

 tiary rocks, and species believed to belong here have even been found in 

 the Mesozoic deposits. Yet two families, Coccidte and Psyllidii?, occur witli 

 us, and have not yet been found in European rocks, though Coccidfe are 

 known from the Baltic amber. In all we find represented six families, thir- 

 teen subfamilies, fifty-five genera, and one hundred and twelve species in 

 the four hundred specimens that have been examined. 



The families Coccidae and Psyllidaj, however, are very feebly repre- 

 sented by a few examples only, the great bulk of the fossils both in Eu- 

 rope and America belonging to the four families. Aphides, Fulgorina, 

 Jassides, and Cercopidse ; in each of these, with the possible exception of 

 the Jassides, the variety and abundance of forms is greater in America than 

 in Europe, even including the types from amber, while a comparison of the 

 rock deposits alone would show a vast preponderance on the American side. 

 In individuals the Cercopidse easily hold the first rank, and this appears to 

 be true in Europe as in America; next follow the Aphides, for which in 

 variety of type and in interest America far excels. The Jassitles appear to 



