EQUISETITES. 23 



Genus EQTJISETITES, Steinberg. 

 [Flor. Vorwelt, vii. 1838, p. 43.] 



A general name applied to such fossil remains as closely resemble 

 the recent genus Equisetum. 



Brongniart, 1 Schimper, and other authors use the term Equisetum 

 for the fossil representatives of that genus; as the former has 

 pointed out, there are several species which from the character 

 of the fertile as well as the sterile stem structures cannot be 

 separated from the recent genus. So far as we are able to judge, 

 this appears to be the case; but as yet we are in the dark as to the 

 histological structure of the fossil forms, and, with such material 

 as palseobotanists have to deal with, there cannot be any certainty 

 as to the exact connection between the living and fossil equise- 

 taceous plants. In addition to this necessary imperfection of the 

 fossil material, there is another argument in favour of some slight 

 distinction in the name used for species other than those now in 

 existence, namely the fact that we thus have a convenient distin- 

 guishing mark between recent species of Equisetum and their 

 geological representatives. 



Owing to the absence of internal structure in the fossil repre- 

 sentatives of the Equisetacea our exact knowledge of the ancestral 

 forms of Equisetum leaves much to be desired. Graf Solms has 

 called attention to this fact in his " Fossil Botany," 2 and he gives a 

 short critical account of the geological history of the sole surviving 

 genus. A few examples have been recorded from the Coal-Measures 

 of different countries, but as a rule there is very little to be learnt 

 from them. Without attempting any review of the older equi- 

 setaceous plants, it is of interest to note that there appears to be 

 some evidence for the existence of this family in Britain during the 

 Coal-Measures period. Kidston 3 has recently figured and described 

 part of a sporangiferous spike which seems to resemble the fertile 

 apex of a recent Equisetum stem. This new species from the 

 Coal-Measures of Yorkshire is named Equisetum Hemingway*. 



1 Brongniart, Tableau, p. 46. 



2 p. 175. 



3 Annals, vol. ix. ser. vi. 1892, p. 138. A Permian species, E. Tauj'olyi, has 

 recently been recorded by Professor Zeiller from Commentry. (Saporta, Rev. 

 gen. bot. vol. v. 1893, pi. iii. p. 179.) 



