This book by Oliver Perry Hay is a comprehensive study of the Pleistocene period in North America. It covers the various species of vertebrate animals that inhabited the region during this time, including mammoths, mastodons, and giant ground sloths. The book provides detailed descriptions of their anatomy, behavior, and distribution, and examines the way in which these animals interacted with their environment. This book is a fascinating glimpse into a prehistoric world that few people are familiar with.

This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.

This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.

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