then may have supported enough oak to have allowed the extension of some species of the typically Californian fauna.
Within California the paths of migration of the several species of Antron and Besbicus probably began at some point in the eastern part of the state and extended north and south and about the Great Valley. The Valley was not completely cut off from the sea until the Pliocene and Pleistocene. The
present-day range of many plants and animals of the foothills of the mountains rimming the Great Valley may be due not only to differences in topography and climate and vegetation at different elevations, but to the influence of the more ancient distribution as well. Altho many Cynipidae range all the way from Bakersfield in the southern end, to Shasta Springs at the extreme northern end of the Valley, and altho many of the species of the foothills and even higher elevations of the Sierras find no barrier in the latitude of San Francisco, many
