56 EftTIISETITES. 



of the thin coal-seams of the Estuarine series ; the occurrence of 

 an argillaceous bed crowded with small roots immediately below 

 the coal has suggested a comparison with the nnderclays of the 

 Coal-measures. 



Konig's species Oneylogonatiim carlona/rium,^ from the Brora 

 Coalfield of Sutherland, is no doubt identical with HquisetUes 

 columnaris of the Yorkshire rocks ; the coal-seams of the Brora 

 district are considered by Konig to have been formed, in part 

 at least, from the remains of the reed-like plants to which he 

 applied the above name.' 



In 1829 Phillips' published a figure of a slender fossil stem 

 from Saltwick under the name Equisetum laterals, characterized 

 by the occurrence of small circular areas of a wheel-like pattern 

 on the intemodal region. The same form of stem was also figured 

 and described by Lindley & Hutton " in 1836 ; by these authors 

 the circular discs aie compared with the phragma of a Calamite. 

 They remark that similar discs were said to occur as isolated 

 objects on the surface of the shale (on the authority of 

 " Mr. "Williamson, jun." — the late Professor "Williamson). In 

 1851 Bunbury^ discussed another example of Phillips' species, in 

 which narrow spreading leaves were given off from the node as in 

 AsterophylUtes. The fossil represented in Text-fig. 3 (No. 40,561) 

 is probably the one which Bunbury had before him, and it is 

 certainly the specimen figured by Zigno as Calamites lateralis. 

 The long ' spreading leaves ' of these authors are no doubt slender 

 branches, the true Equisetaceous leaf-sheath being faintly shown 

 as a series of small pointed teeth just above the nodes. Heer, misled 

 no doubt by the descriptions of Bunbury and Zigno,* proposed to 

 transfer Phillips' species to the genus Phyllotheca, and Schimper ' 

 substituted the generic name Sokizoneura. The circular discs on 



' Konig, in Murchison (29). 



' Zigno (39), p. 113. Zigno considered the Brora fossil specifically distinct 

 from H. columnaris, and proposed to adopt the name .E. Komigii in place of 

 Konig's designation. 



' Phillips (29), pi. A. fig. 13. 



* Lindley & Hutton (36), pi. 186. 



5 Bunbury (61), p. 189. 



« Zigno (66), p. 46. 



' Schimper (69), p. 286. 



