EQUISETITES. 29 
they can all be referred to one species; many of them were no doubt 
unnecessarily separated by Dunker, but in the case of Carpolithus 
sertum and C. Brongniarti we do not recognize the characteristic 
form of Lyuisetites Burchardti tubers, nor is it easy to account 
for the differences by such causes as Schenk has suggested. 
In the third edition of Dixon’s ‘‘ Geology of Sussex,” Carruthers! 
suggests that the tubers of #. Burchardti from the Isle of Wight 
may be identical with Mantell’s ‘‘seed-vessels of estiacea,” 
described in the ‘‘ Wonders of Geology,’* from the Heathfield 
ironstone. Schenk? refers to Ettingshausen’s figures of Lguisetites 
Burchardti and Carpolithus Lindleyanus as representing respectively 
a Calamitean branch, and a fragment of Walchia. The figures of 
the former appear to me, however, to have been correctly named 
by Ettingshausen ; the Carpolithus may be a fragment of Walchia, 
as Schenk suggests. Fontaine’s species, Hyuisetum virginicum,* 
from the Potomac beds of America, agrees fairly closely with 
E. Burchardti. 
Although I have not included in the above synonymy a Japanese 
species, 4. Ushimarense,® recently described by Yokoyama from 
beds which he speaks of as Jurassic, it is by no means certain that 
his specimens should not be referred to the European species. 
His description is very meagre, and the figured specimens not 
particularly well preserved, but there is an obvious resemblance to 
E. Burchardti; this is admitted by Yokoyama, who points to the 
similarity in the form of the tubers. His short account of the 
branches agrees with that given by Schenk for the North German 
specimens, e.g. cf. Yokoyama’s fig. 3, pl. xi. and Schenk, pl. 
xxi. fig. 1. In spite of the close resemblance, it is probably 
better to retain Yokoyama’s new name; the slight difference in 
shape is not of great specific value, but it is the chief feature 
afforded by the imperfect materials. Further discoveries in the 
Japanese plant beds may establish a specific distinction on a 
firmer basis, or, on the other hand, may afford stronger evidence of 
specific identity. 
1 p. 282. 
2 Edit. iii. p. 372. 
3 Paleontographica, p. 206. 
4 Potomac Flora, p. 63. 
5 Journ. Coll. Sci. Japan, vol. iii. 1890, p. 39, pl. xi. figs. 1-3. 
