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 | 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, | 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, ser. 4, t. 3, 1903, p. 468. 
