L. P. WARD — PLANTS OP THE AMERICAN TRIAS. 



29 



Summary of the geologic and systematic Distribution of American Triassic Plants and 



their A /Hex. 



In this table the classification of the several types of vegetable life has been intro- 

 duced. It will be seen that there are represented among the plants that have a 

 foreign distribution ferns, Equiseta, rhizocarps, cycads and conifers. Considering 

 the geological range, we observe that it extends from the Buntersandstein to the 

 Potomac formation or lower Cretaceous ; but if we scan the columns closely we per- 

 ceive that none of our species actually occur above the Oolite, the only forms here 

 compared in the Wealden and Potomac being forms allied to American Triassic 

 species. On the other hand, it is remarkable that the largest number of identical 

 forms occurs in the Keuper. This results from the very large number that Dr. Stur 

 has identified with the plants of the Keuper of Lunz, Austria, and those of Raibl, 

 in Carinthia, and of certain localities in Switzerland, referred to about the same age. 



I have summed up the general results of my investigation of the American Tri- 

 assic flora both from the geological and botanical standpoints in the final table 

 (page 30), to which I now call attention. 



We perceive by inspection of this table that the Mora consists of 119 specific 

 forms, which may for convenience be called species, though many of them are not 

 specifically determinable and in a few cases they consist of varieties. These 119 

 species belong to 51 genera, although of the 51 a few are not distinctly named as 

 genera and some may be merely the fruit of the same genera that are also found in 

 other forms. 



Looking to the botanical affinities of these forms, we find that the most of them 

 can be classified under some of the general grand divisions of the vegetable king- 

 dom, although in a few cases this determination is very uncertain. We thus have 

 what seem to he representatives of eight great types of vegetation. These types, 

 beginning with the lowest and naming them in the supposed ascending order of 

 their Structure, are, first, fucoids, that is some kind of seaweed ; second, terns ; third, 

 equiseta; fourth, lycopods ; fifth, rhizocarps ; sixth, cycads ; seventh, conifers ; and, 

 eighth, monocotyledons. There remain five genera and six species w hose botanical 

 affinities are whollv unknown. 



