LOCALITIES 3 



from which he gathered a considerable collection which 

 has been described by Albert Gaudry in various papers 

 mostly in the Annales de Paleontologie. 



These two collections and their collaborations represent 

 all the work thus far done on the Deseado beds and fauna. 

 Our collection is the first one of any considerable size to 

 be brought to North America, and it seems to be by far the 

 most complete, the various animals being represented by 

 more complete skeletons than in any of the previous col- 

 lections. 



The beds were first designated as the Pyrotherium beds, 

 and are always so referred to by F. Ameghino. Tournier 

 and Gaudry, feeling the prejudice which is fairly general 

 among Palaeontologists against names based on any con- 

 tained animal (which may or may not be present at other 

 localities, which may extend through more than one 

 period, and whose name may be changed as a result of 

 further knowledge) used the term Deseado formation, as 

 his collections came from the neighborhood of this river. 

 This is a geographical name and avoids the chance for 

 confusion; so I have adopted it throughout this paper, it 

 being understood as an equivalent of the term Pyrotherium 

 beds. 



Ameghino never gave the exact, or anywhere near the 

 exact, localities from which his Deseado specimens came. 

 It was not until 1906, when his Formations Sedimentaires* 

 appeared, that any localities were designated, and there 

 on a sketch map he indicates as Deseado exposures, about 

 a dozen points, scattered between the upper part of the 

 Chubut River to some 25 miles south of the Deseado 

 River. These are included in an oval area some 500 miles 

 long by 150 miles wide. Ameghino also suggests on this 

 occasion that the Deseado formation originally extended 

 over at least the whole of this area. As will be seen in the 

 next chapter, I believe that the deposits of this age 

 * Anal. Mus. Nac. Buenos Aires, ser. 3, t. 8, p. 99. 



