402 Mr Vernon, On the occurrence of Schizoneura paradoxa, 



Equisetales. 

 Schizoneura paradoxa, Scbimper and Mougeot, 1844. 



1828, Calamites arenaceus, Brongniart, Hist, veget. foss. PI. xxiii. 



fig. 1. 

 1844. Schizoneura paradoxa, Schimper and Mougeot, Monog. 



Plant, foss. Vosges, p. 48, Pis. xiv. xv. xvi. 

 1844. Calamites arenaceus, ibid. p. 57, PI. xxviii. fig. 2. 

 1844. Catamites mougeoti, ibid. p. 58, PL xxix. figs. 1, 2, 3. 

 1870. Equisetites mougeoti, Schimper, Traite, p. 279, PI. xii. 



1907. Equisetites arenaceus, Arber in Wills' Geol. Mag. Dec. 5, 



Vol. IV. p. 32. 

 1910. Schizoneura paradoxa, Wills, Proc. Geol. Assoc. Vol. xxi. 



Part 5, p. 272. 



Localities. Voltziensandstein (Upper Bunter) of the Vosges. 

 Lettenkohle (top of Muschelkalk) at Neuewelt, Basle, Switzerland. 

 Lower Keuper Sandstone at Bromsgrove and other places in 

 Worcestershire. Bunter Pebble Beds of Nottingham. 



Diagnosis. From a study of tbe specimens in the Strassburg 

 Museum, including the original material of Schimper and Mougeot, 

 and of the Worcestershire specimens, described in his recent 

 paper. Wills* has drawn up the following diagnosis: 



" Large plants, stems up to two inches in diameter, stems 

 divided into nodes and internodes, internodes long, larger stems 

 either ridged or smooth, pith either wholly or partially hollow; 

 branches borne in whorls at the nodes, external surface of branches 

 usually smooth or nearly smooth ; leaves long and strap-like, 

 borne in whorls at the nodes, leaves united either into a sheath 

 or into sheath segments or free to their bases, border of leaves 

 smooth, median part of leaves with fine close-set parallel nerves, 

 cone probably with peltate areas on external surface, roots arising 

 from the nodes, roots small and repeatedly branched." 



Schizoneura must still be regarded as an imperfectly defined 

 genus. Of the cone our knowledge is of the slightest, and of the 

 internal anatomy of the plant we are quite ignorant. The frag- 

 mentary nature of the stem casts renders identification in many 

 cases doubtful or even impossible. Ridged and grooved casts are 

 of common occurrence, some of these may represent the external 

 surface of the stem, or they may be the impressions of the external 

 surface more or less modified by the internal structure, as pointed 

 out by Wills; more usually they are interpreted as pith casts. 

 Such fragmentary pith casts cannot be generically identified, 

 they may belong to one of several members of the Equisetaceae. 



* Wills, " The Fossiliferous Lower Keuper Eocks of Worcestershire," Proc. 

 Geol. Assoc. Vol. xxi. 1910, Pt. 5, p. 272. 



