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certain that they do not afford ground for maintaining that we 
are here dealing with extinct groups any higher than genera or 
at most than tribes. 
Yet there are one or two instances in which extinct groups of 
a higher grade may be found. Thus, in the work already alluded 
to and previously, 1 have drawn attention to a strange type of 
fossil Thysanura, Planocephalus, for which it seemed necessary 
to frame a new suborder, and, though its possible reference else- 
where has been suggested, this suggestion will hardly stand the 
test of investigation, and the matter remains where I left it ; and 
at the present time attention is directed to another group, the 
Coleopterous family Rhynchitidae, in which it has been found 
necessary to establish a new subfamily group for an abundant and 
varied series of insects from our Tertiaries. 
In studying the Rhynchophorous Coleoptera, I have for the 
first time made use of all the material which has been collected 
within the most recent as well as within former years ; and have 
been able therefore to do justice to the other localities of fossil 
insects, as well as the now famous locality of Florissant, Colo., 
and I find that there is no family of American Rhynchophora 
paleontologically more interesting than the Rhynchitidae. In 
point of numbers alone the species of this group form more than 
ten per cent of the fossil Rhynchophora of North America, while 
in the existing fauna the Rhynchitidae comprise less than two 
and a half per cent of all the Rhynchophora. Our recent Rhyn- 
chitidae are separated by LeConte and Horn into two subfamilies, 
one of which comprises the bulk of the family, while a single spe- 
cies is separated to form the other, the Pterocolinae. This differs 
from the Rhynchitinae among other things by the antennae being 
inserted much nearer the eyes, by the wide separation of the fore 
and middle coxae, and by the broad side pieces of the meta- 
sternum. The Pterocolinae are not represented among the fossils, 
but all the genera of Rhynchitinae now existing in our fauna are 
recognized, as well as a new generic type. These, however, are 
but a mere fraction of the fossil Rhynchitidae, the bulk of them 
being separated as a new subfamily, the Isotheinae, a subfamily 
characterized by the moderate separation of the fore and middle 
coxae and by the insertion of the antennae which is before the 
middle of the basal half of the straight and porrect beak. These 
characters show an approach to the Pterocolinae rather than the 
