In order to show the geographical distribution of the most important species that occur in considerable numbers, a series of maps has been prepared, pertaining to the following:
Whales and porpoises. Seals and walruses. The edentates. Elephas primigenius. E. columbi. E. imperator. E. species undetermined. Mastodons, mostly Mammut. Horses, mostly Equus. Tapirs. Peccaries. Camels. Odocoileus. Cervus. Rangifer. Musk-oxen. Bisons, extinct. Bison bison. Giant beavers.
Where the map of a State has become too crowded with numerals, a special map of that State for that species or genus has been prepared. There are maps of the edentates in Florida; mastodons of Indiana, of New York, of Ohio, of Michigan, of Florida; _Elephas columbi_ in Florida; _Elephas imperator_ in Florida; horses in Florida.
Other maps and figures for illustration of the Pleistocene geology will be found in their proper places.
The first part of the present volume is occupied by a consideration of the specimens recorded on the maps. Such information is noted as could be secured, often satisfactory, little enough sometimes; but it has been found that one can not foresee what important information a given fossil may furnish. At least, the presence of the fossil at a locality indicates the existence there of Pleistocene deposits of some kind. In cases where other species have been associated with the one mapped and described, these are noted.
When the consideration of these mapped species and genera is completed, the Pleistocene geology of the various States and provinces is taken up, so far as it is related to the vertebrate palæontology. This involved an examination of much of the literature of the Glacial period; and here one soon finds himself in face of huge tomes and endless articles and detailed maps. Only somewhat less in amount is the literature of the States beyond the glaciated area. The opportunity to misunderstand and to commit errors is unlimited, and the writer can only hope for lenient criticism.
An attempt has been made in the case of all vertebrate fossils to determine their geological relations and to derive some general conclusions regarding the history of our Pleistocene vertebrates and their relation to the divisions of the Pleistocene epoch. The conclusions reached are embodied in the immediately succeeding pages.