EO.UISETITES. 53 



Genus EQUISETITES, Steinberg. 

 [Flor. Vorwelt, v.-vi. p. 43, 1833.] 



1. Equisetites columnar is, Brongn. 



2. Equisetites Beani (Bunb.). 



A generic name applied to such fossil stems as closely resemble 

 the recent genus Equisetum. 



The various species of Equisetites are founded on stems, leaves, 

 and strobili, which occur as casts or impressions, and nothing is 

 known with certainty as to the anatomical characteristics of the 

 fossil forms. The large size of some of the Triassic and Jurassic 

 stems and the fine longitudinal striation occasionally seen on the 

 surface of the casts, render it probable that some at least of the 

 fossil Horsetails grew in thickness by means of the activity of 

 a cambium, as we know to have been the case with the Palaeozoic 

 Calamitean plants. 



It is an unsatisfactory task to attempt to define the distinguishing 

 characters of species of Equisetites, which are usually represented 

 by fragments of rhizomes or aerial shoots. The leaf -sheaths are 

 often imperfectly preserved, and afford uncertain evidence as to 

 specific features ; the differences in the diameter of the stem 

 fragments and in the length of the internodes are often such as 

 might easily occur in the same plant. 



1. Equisetites columnaris, Brongniart. 



[Brongniart, Prodrome, p. 37, 1828.] 

 (PI. XIX. Figs. 1, 3, 4, 5; Text-figs. 3, 4.) 



1828. Equisetum columnare, Brongniart, Prodrome, p. 37. 



. columnare, Brongniart, Hist. veg. foss. p. 115, pi. liii. 



1829. Equisetum columnare, Phillips, Geol. Yorks. p. 153. 

 E. laterale, ibid. p. 153, pi. x. fig. 13. 



Oncylogonattitn earbonarium, Konig, in Murchison, Trans. Geol. 



Soc. [2], vol. ii. p. 300, pi. xixii. 



1833. Equisetites eolumnaris, Sternberg, Flor. Vorwelt, v.-vi. p. 45. 

 1836. Equisetum laterale, Lindley & Button, Foss. Flor. vol. iii. pi. 186. 



1848. Equisetites lateralis, Bronn, Ind. Pal. p. 464. 



1849. Equisetites lateralis, Brongniart, Tableau, p. 105. 



