340 



TERTIARY INSECTS OF NORTH AMERICA. 



Of the other smaller families the only ones which surpass more than 

 five known fossil species in all are the Nabidse with seven species and the 

 Tingididee with eight ; of these there have been found in America no Nabi- 

 dse whatever and the smaller half of the Tingididae. Other families not found 

 in America are the Nepidse, Belostomatida?, Naucoridas, Saldidte, Limnoba- 

 tidse, and Aradidoe, all but the Saldidfe having more than one species in 

 Europe. On the other hand the only family found in America and not in 

 Europe is the Acanthiida? with a single species. The remaining smaller 

 families represented on both continents vary in their numbers from one to 

 three in America and from one to four in Europe. 



If, however, we omit from this enumeration the forms which have been 

 found in amber, and thus compare those of the rocks only, as in the follow- 

 ing table, we shall meet with somewhat different results. 



Table of fossil He tei'op tera from rock deposits. 



