PREFACE The results of the Amherst Patagonian Expedition were divided into two parts, the general features, together with the narrative, were reported in a separate volume entitIed, Hunting Extinct Animals in the Patagonian Pampas, published in 1913. Far this volume has bccn reservcd the description of the materiaI found and such conclusions as are dircctly derived from that material. The material on which this work is based has been prepared on and placed on exhibition at Arnherst College. The material here described forms a unified body of data, which adds materially to our knowledge of the complete animals of the Tertiary period in Patagonia. There are besides this some small collections which offer some isolated new facts, but the working up of thesc has been reserved for the future for small articles, as the work may come to maturity.