62 EQTJISEIITES. 



concave median portion of each leaf-segment, the outlines of the 

 epidermal cells may be readily detected, and the slightly raised 

 edges hear numerous small irregular tubercles, which may be due 

 to the presence of siliceous deposits in the epidermal cells. On 

 some of the nodes five branch-scars are shown ; these alternate in 

 position with the soars on the next node. This fOrm of stem may 

 be compared with the type of Calamitean cast known as Calamites 

 {JEuoalamites) eruciatus, Stemb., from the Coal-measures.^ 



Egerton Coll. 



\ •■■ . =, 



t' '1 it 



i I > 



Fiu. 4. — Equisetites columnaris, Brongn.' 



A. Part of a stem showing leaf-sbeaths, and an imperfect diaphragm flattened 



on the internode. 



B. A single leaf-sheath. 



C. A nodal diaphragm. 



From specimens in the York Museum. (Block lent by the Cambridge 

 University Press.) 



v. 2613. The smaller of the two specimens bearing this number 

 affords a good example of a cast of the typical Equisetites eolumnwris 



' Seward (98), p. 377, fig. 102. 

 2 Ibid. p. 278, fig. 64. 



