330 J. B. Hatcher — Geology of Southern Patagonia. 



It was found associated with the remains of other mammals, 

 birds and small reptiles. From the stratigraphic position of 

 the beds in which this tooth and the associated fossils were 



FlG. 1, right sup. incisor of Pyrotherium ? three-eighths natural size. 



found I did not suspect that they were in any way related to 

 the Pyrotherium beds and spent very little time in them. 



I seriously question the stratigraphic position of the Pyro- 

 therium beds as determined by the brothers Ameghino, 

 although it may seem presumptuous on my part, since I was 

 unable to identify the beds at all, and the explorations, travels 

 and opportunities for observations in this region of Senor 

 Carlos Ameghino have been far more extensive than have my 

 own. It is certainly remarkable that in these beds containing 

 Dinosaurian remains, associated according to Ameghino with 

 the remains of mammals, some of them, as for example Pyro- 

 therium of immense size, only a little less than that of the 

 elephant and consequently easily to be seen, I could have 

 searched for weeks without ever finding a single mammalian 

 bone, while every day I found Dinosaurian remains. 



Considering the immense size and highly specialized charac- 

 ter of many, in fact of most of the mammals described by 

 Ameghino from the Pyrotherium beds, it does not seem pos- 

 sible that they could have lived in Cretaceous times and coex- 



