ART. 22 TERTIARY FOSSIL PLu\NTS FROM ARGENTINA BERRY H 



Order CYCADALES 



Family CYCADACEAE 



Genus ZAMIA Linnaeus 



m 



ZAMIA AUSTRALIS, new species 



Plate 2, Figure 1 



Frond tiny, ovate lanceolate in outline, about 5.5 centimeters long 

 and 1.4 centimeters in maximum width, consisting of about 32 pairs 

 of subopposite to alternate pinnules. Pinnules oriented at angles 

 of about 65° to the rachis, to the top surface of which they are 

 united by the whole width of their bases. They are entire, strictly 

 linear in outline, and conspicuously truncate at their tips. Their 

 texture is coriaceous and their few veined longitudinally parallel 

 venation is very faint, possibly because the specimens show only the 

 upper surface of the frond. That it is the upper surface seen and 

 that the pinnules are attached to the upper surface of the rachis is 

 shown by the fact that the bases of the pinnules nearly meet and the 

 outline of the broader rachis can be made out beneath their proximal 

 edges. 



This characteristic little form is one of the most interesting in the 

 whole collection. It is based upon two nearly complete specimens 

 and represents the southernmost known extent of the genus in either 

 the past or the present. 



The genus Zajnm, whose species are not at all genetically related 

 to numerous fossil forms that have been described as species of 

 Zamites, contains about 35 existing species, ranging from peninsular 

 Florida, Mexico, and the Antilles through northern South America 

 and along the eastern and in that region wetter Andean slopes to 

 eastern Bolivia and northwestern Argentina. 



Zamia is the dominant existing cycad genus of the Western Hemi- 

 sphere, and its range in the Tertiai-y was greater than at present, 

 extending to latitude 36° 30' north in the Eocene.^o A South 

 American Pliocene species was recorded by Krasser" from Bahia, 

 Brazil, but was not represented in the collections which I obtained 

 from the same locality. A splendid species occurs in the Arauco coa 

 fields (Miocene) of Chile.^' This last is much larger and quite 

 different from the present form, which is very similar to the small 

 species of Florida with underground stem. 



^0 Berry, Edward W., Torreya, vol. 16, pp. 177-179, figs. 1-3. 191B. 

 " Krasser, F.. Sitz. k. Akad. Wiss. Wien, vol. 112, ab. 1, p. 85.*?, 1903. 

 ^ Berry, Edward W., Johns Hopkins Studies in Geology, No. 4, p. 120, pi. 1, fig. 4 ; pi. 2, 

 figs. 1-3, 1922. 



