563 
[Scudder. 
of North America, comprising a number of species exactly double 
that of the European fossils then known to Heer, it is perhaps 
worth while to offer some observations on the nature of this fauna 
and of its broad relations, on the one hand to the existing hemip- 
terous fauna of America and, on the other, to the tertiary fauna of 
Europe, which in the nearly forty years since Heer wrote has been 
more than doubled. It is the more desirable, as it is the first op- 
portunity that has occurred of making a comparison in any order 
of hexapod insects in which the numbers in the strata of each con- 
tinent are to be counted by hundreds. 
The whole number of species, indeed, does not greatly differ in 
the two countries, but it should always be kept in mind that there 
are two independent sources of supply in Europe, one the rock strata 
proper, the other the amber deposits of the Baltic and of Sicily, 
which latter America does not possess, or rather does not yet di- 
vulge. In Europe, twenty-eight per cent of the total tertiary fauna 
is made up from amber inclusions, and the total is thereby raised 
as much above the number of American forms as it would be below 
it, were they to be excluded. The following table, in which also 
the relative number of species of each of the two great suborders 
appears, will make this evident. 
TABLE I. TABLE OF KNOWN FOSSIL HEMIPTERA. 
NUMBER OE SPECIES OF 
AMERICAN. 
EUROPEAN. 
HEMIPTERA. 
IN STRATA. 
IN ALL. 
IN STRATA. 
IN AMBER. 
Homoptera. 
112 
102 
56 
46 
Heteroptera. 
154 
201 
162 
39 
Totals. 
266 
303 
218 
85 
I presume it cannot be far wrong to state that the homopterous 
fauna of any given region of considerable extent in the north tem- 
perate zone is to the heteropterous fauna as about one to three ; or, 
in other words, that about twenty-five per cent of the hemipterous 
fauna is homopterous. These figures are the result of the compar- 
isons of several faunal lists. In Mr. Uhler’s “ List of the Hemip- 
tera of the United States west of the Mississippi” (the geographi- 
