NO. 2229. FOSSIL PLANTS FROM BOLIVIA— BERRY. Ill 



than the Potosi flora. I have heard of fossil plants in the lake beds 

 of Sao Paulo through von Ihering, who wrote me of collections having 

 been sent to Kurtz at Cordoba some years ago, but tiiese have appar- 

 ently never l)een described. The only other Soutii American Ter- 

 tiary plants known to me, aside from the record of leaf impressions, 

 apparently uncollected, on the island of Trinidad,^ are the Pliocene 

 plants from the province of Bahia (Brazil), briefly reported upon by 

 Krasser ^ and Bonnet.* Ettingshausen at the time of his death had in 

 preparation an illustrated account of this flora with autotypic repro- 

 ductions of the related existing species, but this unfortunately was 

 never completed. 



It is obvious, then, that the familiar method of ascertaining the 

 age of the Potosi flora by direct comparison with fossil floras of 

 known age in the same general region or even on the same continent 

 is impossible, and it is necessary to rely on a comparison of the Potosi 

 flora with that found in the vicinity of Potosi and on the high plateau 

 of Bohvia at the present time in order to get a measure of the differ- 

 ences in the environments between the two, and then to determine 

 the degree of resemblance between the Potosi flora and that existing 

 in any other part of South America at the present time, and to 

 endeavor to deduce from these criteria its probable age. 



It is perhaps needless to more than mention the existing flora at 

 Potosi or on the high plateau near Corocoro since the rainfall is 

 scanty and both regions are practically treeless and totally incapable 

 of supporting the fossil flora found at these two localities. From a 

 cursory study of Engelhardt's and Britton's determinations I long 

 ago catalogued the Potosi flora as Phocene, and when I began the 

 study of the collections made by SingewaM and Miller, the great 

 resemblance of the majority of the forms, to be mentioned in detail 

 in subsequent paragraphs, to those stiU existing in the rain forests 

 of eastern Bolivia or to characteristic types of the Amazon Basin, 

 led me to even consider these fossil floras as possibly as young as 

 the older Pleistocene. I do not think that the resemblance to the 

 recent flora east of the Andes is overestimated, but the remarkable 

 discovery of a marine Brachiopod in the Potosi tuffs added another 

 factor. It is obvious that the fossil plants could not have grown at 

 Potosi or Corocoro had the front range of the Andes at that time been 

 elevated sufficiently to precipitate the moisture-laden winds that 

 come from the east. At the present time the eastern slopes of the 

 Cordillera Real are very different climatologically and consequently 



1 Wall and Sawkins, Report on the Geology of Trinidad. Mem. Geol. Surv. Gt. Britain, London, 1860, 

 pp. 35-52. 



2 Krasser, F., Ivonstantin von Ettingshausens studien iiber die fossile Flora von Oiiricanga in Brazilien. 

 Sitz. k. Akad. Wiss. Wien, vol. 112, Abh. 1, 1903, pp. S52-860. 



3 Bonnet, Ed., Contribution k la tlore pliocene do la province de Bahia (Br^sil). Bull. Mus. d'hist. Nat. 

 Ann(5e 1905, p- 510-512. 



