INTRODUCTION. 3 



functory manner and no determined effort was put forth toward bringing 

 to light the abundant wealth of the region in the remains of extinct life. 

 In 1887 Senor Carlos Ameghino accompanied an expedition to southern 

 Patagonia, and with that year there commenced that series of discoveries 

 which have followed one another in such rapid succession as a result of 

 the vigorous manner in which the work has been pursued by the brothers 

 Carlos and Florentino Ameghino. 



The discoveries of the Ameghinos were of such importance as to arouse 

 the interest of palaeontologists and geologists everywhere. Interesting 

 and remarkable as were their discoveries (for it was really a new world 

 of animal life that was being brought to light, totally unlike anything 

 hitherto known either among living or fossil faunas) quite as startling were 

 many of the theories advanced by Dr. Florentino Ameghino, concerning 

 the age of the various beds and the relation of the fauna to certain ex- 

 tinct and living animals of the northern hemisphere. For several years 

 geologists and palaeontologists everywhere had realized the importance of 

 the work being carried on by the Ameghinos, though at the same time 

 recognizing the necessity of making a thorough study of the Tertiary and 

 Cretaceous deposits of Patagonia together with their contained fossils, in 

 accordance with the more careful and painstaking methods which have 

 been developed in the northern hemisphere during a half century by a 

 great number of trained and skilled observers, belonging to two genera- 

 tions. It was believed that, when the light of all that had been discovered 

 bearing upon the geological sequence and development of animal life as 

 worked out in the northern hemisphere had been thrown with its full 

 force upon those of the southern, many of the apparently conflicting 

 observations and theories set forth by the Ameghinos would prove invalid, 

 while the main facts would be found to harmonize with those already well 

 established in the north. It was for this purpose that the Princeton 

 University expeditions to Patagonia were organized and carried out by 

 the present writer, when Curator of the Department of Vertebrate Palae- 

 ontology of that institution. 



While the primary object of the undertaking was to make observations 

 and collections bearing upon the geology and palaeontology of the region, 

 such attention as was possible, considering our limited equipment, was 

 given to other branches of natural history. Without wishing to apologize 

 in any way for the character or magnitude of the work accomplished, of 



