34 EQUISETITES. 



In Figs. 3 and 3* we have examples of more perfect tubers. 

 The tubers figured by Dunker under the name Carpolithus sertum 

 agree very closely with some of the English specimens; but the 

 absence of any definition of the North German species prevents 

 us adopting Dunker's name, even if we regard his specimens as 

 identical with ours. 



In his second Memoir on the Wealden Flora, Schenk has figured 

 a specimen with numerous tubers under the name Equisetites 

 Burchardti, Dunk. ; this seems, however, to have a closer resem- 

 blance to our new species ; the tubers are narrow and less spherical 

 than those of E. Burchardti. If we compare Schenk's fig. 1, 

 pi. xxii. PalaBontographica, vol. xix. and fig. 1, pi. xxvi. Palaeon- 

 tographica, vol. xxiii. we notice a distinct difference, not only in the 

 shape of the tubers, but in the general habit of the tuber-bearing 

 plant. Schenk's latter figure shows some of the tubers joined end to 

 end ; the same kind of arrangement occurs in some of the English 

 examples, e.g. V. 2365a. It is, perhaps, not entirely satisfactory 

 to have to rely upon certain differences in the shape of tuberous 

 internodes in determining specific definitions; but in the present 

 instance the available material appears to show well-defined 

 differences, and there is confirmatory evidence in the fact that 

 the two forms of tubers are never found in close association. 



V. 2871. Fig. 2. Internodes 1-1-2 cm. long, about 2 mm. 

 broad. The sandstone matrix is penetrated by stems and root 

 fragments; portions of tubers. Cf. E. urchardti, Dunk., pi. i. 

 fig. 5. Ecclesbourne. Beckles Coll. 



V. 2871. Fig. 3. A few well-preserved tubers ; two shown 

 in place at one node ; fragments of roots. Nodes not clearly 

 marked, no ribs on the internodes, the latter about 1 cm. in 

 length. Ecclesbourne. Becldes Coll. 



V. 2335. Fig. 3*, p. 33. Numerous tubers, some attached to 

 the slender stem. Ecclesbourne. Rufford Coll. 



V. 727. Several tubers, with stem fragments; many of the 

 former show surface depressions due to shrinkage of the tuber 

 tissues. Ecclesbourne. Dawson Coll. 



V. 2365. Five specimens. No detail shown. Ecclesbourne. 



Rufford Coll. 



