12 PROCEEDINGS OF THE NATIONAL MUSEUM vol.73 



The existing southern limit of Zamia is about 25° south latitude, 

 the Chilean Miocene occurrence is about 38° south, and the present is 

 in about latitude 41° 30' south, thus over 6^^° south of the existing 

 range, 



Occun^ence. — Southeast side of Rio Nirihuao, near Casa Piedra, 

 about 12 miles south of Lago Nahuel Huapi, Territory of Rio Negro. 



Holotype.—Qiit. No. 37857, U.S.N.M. 



Order ARAUCARIALES 



Family ARAUCACEAE 



Genus ARAUCARIA Jussieu 



ARAUCARIA NATHORSTI Dusen 



Plate 2, Figures 5, 6 



Araucaria nathorsti Dusen, Svensk. Exped. till Magellanslanderna, vol. 1, No. 4, 

 p. 105, pi. 12, figs. 1-13, 1899. 



This species was described by Dusen from the lignitic shales near 

 Punta Arenas, where it is so abundant that this horizon was christened 

 the Araucaria stage. Dusen distinguishes between the leaves of 

 sterile and fertile twigs, the latter being usually larger, broader, and 

 more ovate (triangular of Dusen), with a broader decurrent base. 



The smaller leaf figured is identical with Dusen's, Figures 5 or 11, 

 but the larger, which predominate in the present collection, are larger 

 and more produced pointed than any he has figured and have more 

 veins than the smaller leaf. The smaller have 12 to 13 veins and the 

 larger about twice as many. While inclining to doubt the possibility 

 of assigning the detached fossil leaves to sterile or fertile shoots, I 

 see no reason to doubt that the present collection represents the same 

 species as that described from the Straits of Magellan. 



Dusen compared the fossil with the existing Chilean pine, 

 Araucaria imhrlcata Pavon, and the similarity is as close as might 

 be expected. If the two occurrences are identical in representing 

 Araucaria natJiorsti^ this species ranges from about 53° south to 

 nearly 41° south, or over nearly 12° of latitude, and this is in accord 

 with the numerous occurrences of petrified wood of the Araucarioxy- 

 ion type which has been reported by many explorers in various parts 

 of this region. The fossil differs from the existing Araucaria hra- 

 siliana in its more coriaceous texture, in which respect it is much 

 more similar to Aranearia inibticata^. differing from both in the less 

 contracted base. 



