"The list on the following pages provides the current names for most of the species described in Grabau's book .... The list is by no means complete and may be subject to revision as more research is done .... [It does, however] provide . . . information for accurate identification of most of the species found in the rocks covered. Detailed stratigraphic information on the occurrences of these species in the local rocks is currently being revised and compiled."(p. iii)