Scudder.] 
570 
[April 2, 
forms in both worlds belongs to the series allied to Jassus and By- 
tlioscopus and not to that of which Tettigonia is the type, so that 
the resemblance of the tertiary fauna in the two worlds is not slight, 
though rarely the same genera appear to be preserved. 
If the number of individuals be regarded, the Cercopidse were the 
prevailing type of Homoptera in tertiary times. At Florissant they 
appear to form three-fourths of the whole bulk. As compared with 
the Fulgorina they were there slightly less numerous in species and 
genera, but five times as numerous in individuals. Most of the ex- 
tinct forms have been referred by authors, and especially by Germar 
and Heer, to the^ existing genera Cercopis and Aphrophora, but 
these references were so far incorrect that in several instances they 
belonged to the alternate subfamily and not to that to which they 
were referred. As to our own species, some of them are gigantic, 
nearly all large, and by far the greater part of them allied to types 
now found only in the tropics of the New World ; and yet I have 
been unable in any instance to refer them to existing genera, though 
doubtless some of them will be found so referable. 
Passing now to the Heteroptera, which form the larger part of 
the Hemiptera both recent and fossil, we find that of the twenty 
families into which the known fossil species may be divided, only 
five are remarkable for the abundance of their representation in the 
existing fauna. These are the Reduviidse, Capsidse, Lygseidse, 
Coreidse, and Pentatomidse, and these same families are also well 
represented among the fossils, containing together about four-fifths 
of the total heteropterous fauna. Indeed the only other family 
which can be regarded as at all abundant in tertiary times is the 
Physapodes, the known species surpassing those of the Reduviidse. 
Of these six families, the Lygseidse were then the most abundant, 
containing a little more than twenty-five per cent of the whole, fol- 
lowed hard by the Pentatomidse with a little less than twenty-five 
per cent ; the Coreidse come next with fifteen per cent, followed at 
nearly similar distance by the Capsidee with nine per cent. The 
Physapodes have seven per cent and the Reduviidse only four and 
a half, mainly because America is so strangely poor in this group, 
having indeed but a couple of species, the only groups at all com- 
mon in America being the four with the highest percentages ; here 
the relative percentages in the two worlds are very different, as will 
appear from the following table, the Lygseidse having thirty-three 
