Report upon United States geological surveys west of the one hundredth meridian, Volume V: Zoology

The subject of the geographical distribution and variation of our western zoölogy is one that has of late years attracted more than ordinary attention from our naturalists; and, as appropriate to the subject-matter of this volume, it is here proposed to give a brief résumé of their conclusions and generalizations, as far as they may be deemed applicable to the special natural history work of the geographical surveys west of the one hundredth meridian.