LYGINODENDRON 385 



foliage of Sphenopteris Hbninghausi} The leaves of this 

 species, which are very perfectly preserved as impres- 

 sions, from the same horizon to which the specimens of 

 Lyginodendron oldhamium belong, were of large size, 

 and highly compound — tripinnate or more. There are 

 various other species of Carboniferous Fern-fronds of 

 very similar habit, and it is quite possible, as M. Zeiller - 

 has suggested, that all may have belonged to stems of 

 the Lyginodendron type. 



The arrangement of the Sphenopteris leaves on the 

 Lyginodendron stem, in ^ phyllotaxis, has already been 

 mentioned, and appears to agree with that of the 

 specimens described by M. Zeiller. In the .drawing 8 

 reproduced in the Frontispiece, an attempt has been 

 made to give a restoration of the plant, as it would 

 have appeared in nature. The slender stem (of which 

 only the lower part could be included in the figure) is 

 shown somewhat inclined, to indicate that it was 

 probably supported by other plants. Its surface bears 

 the characteristic spines, and shows traces of a 

 reticulated cortical structure. The arrangement and 

 form of the large, highly compound leaves are known, 

 from the evidence given above, to be essentially true to 

 nature, the lamina of the leaf having been copied from 

 that of Sphenopteris Hbninghausi, The forking of the 

 main rachis, however, does not come out in the figure. 

 The position of the branching adventitious roots on the 



1 Zeiller, Bassin houiller de Valenciennes, p. 84, Plate vi. Fig. 1, 1886. 

 See also Kidston, " Microsporangia of Pteridospermeae," /VhY. Trans. R.S. 

 B, vol. 198, 1906. 



2 Zeiller, " Obs. sur quelques fougeres des depots houillers d'Asie 

 Mineure," Bull. Soc. Bot. de France, vol. xiv. p. 195, 1897. 



3 Prepared,, according to my instructions, by Mr. J. Allen, a skilful 

 botanical artist. 



