608 F. AV. KXOWLTOX MESOZOIC FLORAS OF THE AMERICAS 



cate aridity is really valid — ^it is not altogether accepted — it might ac- 

 count to some extent for the absence of plant remains in certain very 

 thick and generally barren deposits. 



Bnt, be these controlling factors what they may, the fact remains that 

 the known Triassic flora is but scantily preserved to ns. In addition to 

 the scantiness of the plant remains, there is another element that must 

 be mentioned, namely, the authenticity of the reference of certain deposits 

 to the Triassic. Though quite generally considered as referable to this 

 epoch, there is some lack of confirmatory data — that is, in the absence of 

 thoroughly satisfactory information it is often difficult to decide between 

 Upper Triassic and Lower Jurassic. 



The Triassic flora of Xortli America north of Mexico numbers 136 

 nominal species. Of this number about 120 species are confined to the 

 eastern province — that is, to Massachusetts, Connecticut, Penns3'lvania, 

 Virginia, and Xorth Carolina. The remaining 16 forms are distributed 

 as follows: Abiquiu, Xew Mexico, 11 species; fossil forests of Arizona 

 and vicinity, 4 species ; and Alaska, 1 species. 



Passing south into Sonora, Mexico, it is to be noted that Newberry 

 described a small collection belonging to 9 genera and 13 species that 

 were supposed to be in the same stratigraphic position as those at Abiquiu, 

 New Mexico, though only one species is common to the two areas. From 

 the so-called Mixteca Alta, or high country, on the southern edge of the 

 Cordilleran system facing the Pacific, in the Mexican State of Oaxaca, 

 Wieland has reported the presence of Triassic plants ; but it is my opinion 

 that these plants are younger than this, though it is not definitely settled 

 just what their position is. 



In 1888 Newberry- reported the presence of Ehastic plants from San 

 Juancito, Honduras, enumerating 11 genera and 14 species. In a num- 

 ber of subsequent publications Carl Sapper^ has intimated that New- 

 berry's age determinations should be accepted only with doubt; they are 

 possibly Jurassic. 



Passing now into South America, so far as I am able to determine the 

 first plants of supposed Triassic age were reported by Zeiller,* in 1875, 

 from La Ternera, northern Chile. They were found in a rather impor- 

 tant coal-basin and comprise only six species, belonging to the genera 

 Jeanpaulia, Angiopteridium, Pecopteris, Dictyopliylhim, Podozamites, 

 and PaUssya; they were referred to the Rhfetic. 



2 J, S. Newberry : Am. Jour. Sci., 3d ser., vol. 36, 1888, pp. 842-351. 



3 Bol. Inst. geol. Mexico, no. 3, 1896, pp. 5-8. 



* R. Zeiller : Note sur les plantes, fossiles de la Ternera (Chili). Bull. Soc. geol. de 

 France, 3d ser., vol. 3, 1875, pp. 572-574. 



