ORTMANN : TERTIARY INVERTEBRATES. 305 



Natica chiloensis N. ovoidea. 



Turritella exigua T. ambulacrum. 



Struthiolaria liatcheri S. ameghinoi (and ornatd). 



Bulla remondi B. patagonica. 



Since these genera belong to the most characteristic forms of these de- 

 posits, it is very significant that they are represented by different species, 

 and this fact affirms the difference in age of both series indicated by the 

 stratigraphical evidence. 



The fact that 4 Navidad species have been discovered in the Magel- 

 lanian beds suggests that this latter horizon is also represented within the 

 Navidad series. In this respect it is significant that these Navidad species 

 have never been found in Patagonia, and it is quite possible that the 

 Navidad fauna as described by Philippi contains elements of different age, 

 including the Magellanian beds. 



As regards the age of the Magellanian beds we must depend in the first 

 line on the stratigraphy, since palaeontology although suggestive of a 

 slightly older age than Patagonian is altogether insufficent to permit 

 any definite opinion. The Magellanian beds are several hundred feet be- 

 low the Patagonian, and are separated from them by a coal deposit ; since 

 the Patagonian beds are Lower Miocene, this would bring the Magellanian 

 beds into the Oligocene, or perhaps taking into consideration the changed 

 conditions under which the Upper Lignites were deposited into the 

 Upper Eocene. 



It would be very interesting and important to get more material from 

 the Magellanian beds. This first indication of this fauna was given by 

 Philippi (1887), who described a number of fossils from Punta Arenas 

 and Skyring Water. From his list of 16 species (leaving out Turritella 

 patagonica, which has been inserted by mistake) the following are repre- 

 sented in our collection : 



Haliotis imperforata = Crepidula gregaria. 



Venus chiloensis. 



Panopea ibari. 



Pectunculus ibari and magellanicus (both identical and = Glycimeris ibari). 



Ostrea bourgeoisi and patagonica (both identical and = . ingens). 



Ostrea torrcsi. 



Two of these belong in the Magellanian beds (Panopea ibari and Ostrea 

 torresi], while the rest has been found in horizon V, which represents the 

 Patagonian beds. 



