As to the beds underlying the Patagonian, I am sure that a considerable study of the marine series is still requisite to determine the relationships of the beds in different parts of Argentine, and their relative positions as compared with beds in other countries. Ameghino appended to his paper on the Formations Sedimentaires a section of the strata exposed on the coast of Patagonia from Rio Negro to Cape Virgenes, on which from above Punta Atlas south to below Pico Salamanca, the Casamayor (= Notostylops) beds fill the interval from the Salamanca formation up to the Patagonian. On the strength of this map I followed these beds the whole distance looking for vertebrate fossils of Casamayor age. Nowhere did we find a Casamayor fossil. Instead at several points we did find marine fossils. I can not but feel that these beds are plotted as Casamayor, because of their resemblance in color and general texture to the beds carrying the Notostylops fauna at Casamayor. Of several sections of these beds I pick out two as typical, and also because they are near the locality which we worked for the Deseado fauna. On the map they are indicated as A and B. The former passes through a bed of green sands which is, I think, the locality indicated as his northern locality for the Pyrotherium fauna. [Illustration: Fig. 3. Section at _A_ on map page 5, showing strata from sea level up to the Patagonian.] [Illustration: Fig. 4. Section _B_ on map, page 5, showing strata from sea level up to the Patagonian.] From Punta Atlas to Pico Salamanca, Ameghino plots at or just below sea level a bed known as the Salamanca, being typically developed opposite Pico Salamanca. In this in the neighborhood of Pico Salamanca we found the fauna typical of this horizon. Ostrea rostigera v. Ih. Ostrea riongrensis v. Ih. Ostrea ameghinoi v. Ih. Chlamys salamanca v. Ih. Rostellaria striatissima v. Ih. Rostellaria sp. Cytherea calcedonica H. Discinia sp. Diplodon sp. This Salamanca formation is considered by Wilckens as the equivalent of the Roca as exposed on the Rio Negro, and to the Luisa as exposed on the Rio Coyle. All agree that the Salamanca is Upper Cretaceous and a period when Patagonia was covered by the ocean. In section B we found the above fauna in layer 1 which is just above sea level here. In layer 2 we found casts of delicate marine shells (30 to 40 in number), representing four or five species and as yet undescribed. They seem to represent a deeper water facies of the Salamanca. In fact all the shales represented by layers 1 to 5 evidently belong to the Salamanca. Layer 5 was distinguished by having in it at a point some 200 yards north of the section line a quantity of turtle shell fragments.