134 Annals Entomological Society of America |Vol. VIII, 
In Lepidoptera, Psychomorpha, Acoloithus, our Blasto- 
baside. 
In Orthoptera, Stenopelmatus, Ceuthophilus, Hippiscus. 
In this fauna there was apparently no Cicadide, no Mantide, 
nor Mantispide, no Mutillidea, no Ascalaphide, no Myr- 
meleonidz, no Emeside, and few forms of a number of families, 
now fairly well represented here. These came in later from 
the South. 
4. Genera (and derivative genera) representing the hol- 
arctic fauna shoved down by the advance of the ice-sheet, and 
left well scattered by the retreat of the ice-cap. These are the 
forms that show the relationship of our insect fauna particularly 
that of the Eastern States (and British America) with the insects 
of Northern and Middle Europe. The bulk of many large fam- 
ilies belongs to this section, which is most prominent in the 
spring. 
In the Neuroptera, nearly all the Trichoptera, probably 
Panorpa, Hemerobius, Chrysopa in part, several genera of 
Odonata as Sympetrum, Aeschna, Cordulia. 
In Coleoptera, much of the Carabide, Staphylinide, etc. 
In Hemiptera, many Capsids, Lygezids, and Corixa, Jasside, 
Aradide, Corizus, Salda. 
In Hymenoptera, many Tenthredinide, Ichneumonide, 
Osmia, Bombus, Andrena, Crabro. 
In Diptera, many Muscide, Anthomyiide, Syrphide, and 
genera in nearly all families, as Bombylius, Pipunculus, Syrphus. 
In Lepidoptera, many Noctuide, Geometride, and genera 
all through the order. 
In Orthoptera, Tettix, Gryllus, Decticus, Podisma. 
This element is recognized by all entomologists; possibly the 
lower borders of this Holarctic fauna was contiguous to the 
previous element, and represented by the Florissant fossils; 
but I am inclined to believe that these fossils show more relation 
to a Western fauna rather than to a northern one. 
5. Genera representing a comparatively recent influx from 
the American Tropics, a migration still in progress. To this 
belong our Mantispide, much of Myrmeleonide, Ascalaphide, 
Mantide, Cicadide, Mutillide, Brenthide, much of the 
Reduviide and other Heteroptera, many genera as Acordulecera, 
Pepsis, Allochrysa, Resthenia, Heterinia, Callibetis, the Ana- 
