2 THE DESEADO FORMATION OF PATAGONIA 



trips covered the country from Chubut down to the 

 Straits of Magellan, and the various formations from the 

 Lower Cretaceous to the Pampean or Pleistocene. Carlos 

 Ameghino and his brother, Florentino, for years explored 

 in Patagonia, going summer after -summer at their own 

 expense, and in the meantime maintaining a small hook 

 and stationery store in La Plata, the profits of which gave 

 the two brothers a living and furnished the funds for the 

 continual expeditions. In the back of the store was the 

 workshop from which came the continuous stream of 

 knowledge in regard to these strange faunas. One of the 

 best pieces of work done by the brothers was the collect- 

 ing and describing of the fauna of the Pyrotherium beds 

 the bulk of which is contained in two papers entitled, 

 Premiere Contribution a la Connaissance de la Fauna 

 mammalogique des Couches a. Pyrotherium, and Mammi- 

 feres Cretaces de I'Argentine, Deuxieme Contribution, etc., 

 both published in the Boletin del Instituto Geografico Ar- 

 gentino, tomes 15 and 18 respectively. These two papers 

 give names to most of the forms which we found, but the 

 genera and species are based on very fragmentary and in- 

 complete material. It has been a pleasure to find the accu- 

 racy with which these descriptions were made; and our part 

 has been chiefly to supplement and increase the knowledge 

 of the various forms, and to determine from the more 

 complete material the relationships of these strange forms. 

 In some cases we have been able to assemble all the parts 

 of the animals, and in the others to add more or less to the 

 completion of the knowledge of the forms. There is one 

 perculiarity of Ameghino's descriptions, namely the ab- 

 sence of data as to the localities where the forms were 

 found. 



About 1900 Tournier, in the interests of the Paris Mu- 

 seum, made a series of expeditions (5) to Patagonia, on 

 some of which he found a Pyrotherium, or as he has termed 

 it Deseado, locality just south of the Deseado River, 



