The object of this bulletin is twofold: To call attention to the richness of the United States National Museum North American land mammals, and to furnish a summary of the systematic results of the study in this field to the end of the year 1911. North America is understood as the entire continent from Panama northward, together with Greenland and the Greater and Lesser Antilles. In no other museum is the mammal fauna of so large an area so fully represented.

The object of this bulletin is twofold: To call attention to the richness of the United States National Museum North American land mammals, and to furnish a summary of the systematic results of the study in this field to the end of the year 1911. North America is understood as the entire continent from Panama northward, together with Greenland and the Greater and Lesser Antilles. In no other museum is the mammal fauna of so large an area so fully represented

The North American recent mammals in the United States National Museum number about 166,000 specimens, including 1,435 types. More than three-fourths of this material is in the Biological Survey collection, United States Department of Agriculture, the remainder, including the seals, sirenians, ceataceans, and all of the older, more historic specimens, is in the Museum proper. The material derived from these two sources furnishes so complete a representation of the mammals of North America that, of the 2,554 forms now recognized, only 171 are not included.