EQITISETITES. 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 Equisetites 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 E. Burchardti from the Isle of Wight 

 may be identical with Mantell's " seed-vessels of Restiacea" 

 described in the "Wonders of Geology," 2 from the Heathfield 

 ironstone. Schenk 3 refers to Ettingshausen's figures of Equisetites 

 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, Equisetum mrginicumf 

 from the Potomac beds of America, agrees fairly closely with 

 E. Burchardti. 



Although I have not included in the above synonymy a Japanese 

 species, E. Uskimarense, 5 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, pi. xi. and Schenk, pi. 

 xxii. 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 Palaeontographica, p. 206. 



4 Potomac Flora, p. 63. 



5 Journ. Coll. Sci. Japan, vol. iii. 1890, p. 39, pi. xi. figs. 1-3. 



