

XLIl] SEWARDIA 103 



Iii the present state of our knowledge it is impossible to give a 

 satisfactory definition of the genus or to state precisely on what 

 grounds it is separated from Dicranophyllum. In Trichopitys, 

 as represented by T. heteromorpha, the leaves are more variable 

 in form than in Dicranophyllum and less regular in the subdivision 

 of the lamina; there are no persistent leaf-bases like those of 

 Dicranophyllum, but this is a character that could not be seen in 

 imperfectly preserved or partially decorticated specimens. A more 

 important difference would seem to be that in Trichopitys the 

 seeds are borne on special axillary shoots, while in Dicranophyllum 

 they occur on ordinary leaves. Such evidence as we have suggests 

 that Trichopitys is a Gymnosperm possibly allied to the Cordaitales 

 and Ginkgoales, but the facts hardly justify its inclusion in either 

 group. Its affinity to Dicranophyllum cannot be definitely deter- 

 mined though in all probability the two genera are closely related 

 if not indeed generically identical. 



Saporta included in Trichopitys two Jurassic species, T. lacini- 

 ata, originally referred to the genus Jeanpaulia, and T. Lindleyana 1 ; 

 in the latter species he included the specimens doubtfully assigned 

 by Lindley and Hutton to Solenites as Solenites ? furcata 2 . These 

 and other Jurassic leaves that are referred by some authors to 

 Trichopitys are usually regarded as examples of Baiera 3 ; there are 

 no adequate grounds for believing them to be closely related to 

 the Permian Trichopitys. 



Zeiller 4 records a fossil from Triassic beds in Madagascar that 

 he thinks may be an example of Trichopitys. 



SEWARDIA. Zeiller. 



This generic name was proposed by Zeiller in place of Withamia 

 which, in ignorance of its previous use, I employed for some 

 specimens from the Wealden rocks of Sussex. The inclusion of 

 a second species, Sewardia longifolia, necessitates an extension of 

 the definition of the genus to include spinous branches bearing 

 spirally disposed leaves or leaf-like organs, either orbicular and 

 entire or fan-shaped and deeply divided, in the axil of recurved 

 spinous processes. 



1 Saporta (84) PL CLV. figs. 19. 2 Lindley and Hutton (37) A. PL 209. 

 3 Seward (00) B. p. 266. 4 Zeiller (II 2 ) p. 234. 



