THE TRIASSIC PERIOD 



213 



the flora. Fig. 135 gives a good idea of a modern Cycad, though 

 it must be understood that such plants are today relatively 

 unimportant. 



It is generally stated that the plants of the Triassic, except 

 toward the close of the period, in both Europe and America pre- 

 sented a stunted or 

 dwarfed appearance on 

 account of unfavorable 

 (chiefly climatic) en- 

 vironment. Such an im- 

 poverished condition of 

 Triassic plants was at 

 least not universal, for 

 as Knowlton says: "In 

 North Carolina, Virginia, 

 and Arizona there are 

 trunks of trees preserved, 

 some of which are 8 feet 

 in diameter and at least 

 120 feet long, while hun- 

 dreds are from 2 to 4 feet 

 in diameter. Many of 

 the Ferns are of large 

 size, indicating luxuriant 

 growth." l 



Protozoans and Pori- 

 fers were present, though 

 their records are neither 

 very abundant nor of 

 special interest. Part 



Coelenterates. — For 

 the first time the Hexa- 

 coralla, or forms of mod- 

 ern aspect, became ■ abundant, while the ancient (Paleozoic) 

 Tetracoralla dwindled away to extinction. 



Echinoderms. — Crinoids were common, the more ancient 

 types having given way to those of more modern aspect. 



Asterozoans were present. 



Echinoids (Sea-urchins) were common, though most of the 

 1 F. H. Knowlton: Jour. Geol, Vol. 18, 1910, p. 106. 



Fig. 126 

 of a Triassic Conifer, Voltzia helero- 

 phylla. (After Fraas from Scott's "Ge- 

 ology," courtesy of The Macmillan Com- 

 pany.) 



