The chief path of migration of Cynips moving eastward from Missouri probably bent southward about the southern Appalachians and finally up the Atlantic Coastal Plain. The present occurrence of so-called Coastal Plain Cynipidae, or close relatives of Coastal Plain species, across the state of Missouri, thru adjacent parts of the Mississippi Valley, and along the course of the Tennessee River, as well as out on the Atlantic Coastal Plain itself, probably records the path of migration from the Rockies to the easternmost limits of the United States. In the systematic portion of this study data bearing on this point are recorded and mapped under:
| Cynips centricola centricola |
| C. pezomachoides pezomachoides |
| C. pezomachoides derivatus |
| C. gemmula fuscata |
| C. mellea carolina |
The restriction of the short-winged species of each of the stocks of the eastern subgenera to those points which are furthest along this supposed route out of the Southwest, is some further verification of the route. Spreading to the north and to the south of this main path, the ancestral stocks gave rise, by mutation and isolation and, in the few cases noted, by subsequent recombination of characters in hybridization, to the numerous populations which are the species or varieties today. This history is summarized in the phylogenetic maps.
Many will find the present-day species of our genus not easy of identification. There are some who are inclined to believe that species are, after all, but human concepts instead of realities in nature. Some will consider that individuals are so variable and interbreeding Mendelian races so abundant in nature that taxonomic classifications can be nothing but contrivances without biologic significance. And yet, when the Colorado of the West first cut into the Colorado Plateau the specific stocks of Cynips were in existence, and thruout the years that the Canyon has been cutting, even down onto the present, these complexes which we call species have maintained their identity. While the eternal hills have come and gone, these instable protoplasmic, entities have maintained their stability. A stability like that of a stream, with materials always contributing from many sources, with endlessly
