50 Annals of the South African Museum. 



bably of the nature of distally expanded sporangiophores ; but the 

 preservation is unfortunately too imperfect to admit of any satis- 

 factory diagnosis. The cone itself is incomplete and does not show 

 the apical portion ; it is 6 cm. long and slightly more than 2 cm. 

 broad ; the surface is rough and uneven, but shows here and there 

 distinct indications of polygonal protuberances and a few small oval 

 bodies, which may be the terminations of sporangiophores bearing 

 sporangia. The peduncle is represented by an axis 6 mm. broad 

 showing longitudinal striations on its surface. The form of the 

 cone, the appearance of the polygonal prominences and depres- 

 sions, and its association with stems like those shown in pi. ix., 

 figs. 5 and 6, lead me to regard the specimen as a strobilus of an 

 Equisetaceous plant, possibly Schizojieura krasseri. 



Geoup filicales. 



FERNS OP UNCEETAIN SYSTEMATIC POSITION. 

 Genus THINNFELDIA Ettingshausen. 



This generic name was instituted in 1852 for some specimens 

 from the Lias of Steierdorf and defined as follows: — * 



" Eami teretes vel subalati. Folia disticha, alterna oppositave, 

 rhomboidea, ovalia vel lanceolata vel linearia, flabellatim vel 

 pinnatim venosa." 



Ettingshausen's species Thinnfeldia rhomboidalis closely re- 

 sembles the South African forms, and represents a typical 

 example of the genus. The comparison made by the authors 

 of the genus with the New Zealand Conifer Phyllocladus has 

 not been borne out by the investigation of more recently acquired 

 specimens. 



In 1853 Andrae substituted Brongniart's genus Pachypteris for 

 Thinnfeldia and spoke of T. rhomboidalis as Pachypteris thinnfeldia 

 And. t The genus Pachypteris is defined by Brongniart as being 

 characterised by entire pinnules without veins or with a single vein, 

 and is referred by him to the ferns. Zigno's large and well-preserved 

 specimens from the Oolitic rocks of Italy placed in his genus 

 Dichopteris are no doubt generically identical with Pachypteris, 

 but in the Italian examples \ the pinnules are traversed by several 



* Ettingshausen (52), p. 2. f Andrae (53), p. 43. 



X Zigno (56), pis. xii., xiii., xv. 



• 



