4 THE DESEADO FORMATION OF PATAGONIA 



and character have always been local and isolated. We 

 sought for several of these localities and failed to locate 

 them, especially those near Mazaredo, and the northern 

 one on the Gulf of St. George. The point where we did 

 find our material I believe was one of Ameghino's localities, 

 though the settlers of that region had never heard of any- 

 one hunting for fossils there; but the settlement had been 

 practically all within the previous six years, which was 

 much later than the time when Carlos Ameghino worked 

 in the region. 



Beside the foregoing, an exposure of this age is reported 

 by A. A. Romero, just above the fork of the two branches 

 of the Rio Negro, which is some 500 miles north of the 

 first group of localities mentioned. Ameghino also refers 

 to another locality in the Province of Misiones which 

 would be 1,500 miles north of the typical localities. 



The collections made by Tournier for Gaudry came 

 chiefly from an exposure south of the Deseado River, 

 some 15 miles above the mouth of the river.* 



Our collection came from the Chico Branch of the 

 Chubut River, about three miles east of the river, and 

 almost due west of Puerto Visser. As mentioned above 

 on account of the close coincidence of the various species 

 and because Ameghino indicates a locality in the neigh- 

 borhood, I think that our locality is the same as one of 

 his, I should judge it the one from which he obtained a 

 considerable part of his types. This is of importance; for, 

 if in Ameghino's type locality, the determination of the 

 species, as the same as those of Ameghino's, is much more 

 certain. 



In the accompanying map I have indicated the locali- 

 ties given by Ameghino, those of Tournier, and our own. 



*Bul. Soc. Geol. France, scr. 4, t. 3, 1903, p. 468. 



