XIII. Rodents, Cephalomys, Scotamys, Litodontomys, Asteromys, Eosteiromys 185 XIV. Edentata, Proeutatus, Prozaedius, Stenotatus, Proeuphractus, Peltephilus, Palaeopeltis, Glyptatelus, Hapalops, Octodontotherium, Orphodon 197 XV. Marsupialia, Pharsophorus, Notogale, Proborhyaena, Palaeothentes, Pilchenia, Callomenus, Pseuhalmarhippus, Parabderites 210 XVI. Birds, Physornis, Loxornis 225 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 entitled, “Hunting Extinct Animals in the Patagonian Pampas,” published in 1913. For this volume has been reserved the description of the material found and such conclusions as are directly derived from that material. The material on which this work is based has been prepared out and placed on exhibition at Amherst 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 beside this some small collections which offer some isolated new facts, but the working up of these has been reserved for the future for small articles, as the work may come to maturity. The field has only been touched and a vast amount of further work can be profitably done on the horizons immediately preceding and following the one described in this volume, after which an interesting study can be made on the evolution of a fauna which developed in a considerable degree of isolation. F. B. LOOMIS. March 18, 1914. THE DESEADO FORMATION OF PATAGONIA CHAPTER I INTRODUCTION The material described and the conclusions drawn in the following pages are the results of the Amherst Expedition to Patagonia in 1911; an expedition organized and sent out by the Class of ’96 as a part of their fifteenth reunion. The party consisted of Frederic B. Loomis ’96, Phillip L. Turner ’11, Waldo Shumway ’12, and William Stein of St. Joe, Wyoming, and left Amherst July 1, 1911, returning the first of February the ensuing year, having spent its time collecting in the early Tertiary beds of Patagonia, as exposed in the Territories of Chubut and Santa Cruz, the aim being to secure from the earlier periods a fuller knowledge of the vertebrate animals, such as the Princeton Expeditions obtained for the Patagonian and Santa Cruz formations. The narrative of the expedition has been told in “Hunting Extinct Animals in the Patagonian Pampas.”