XXIX] 



LYGINOPTERTDEAE 



37 



cortical stereome on which Brongniart founded the genus Dicty- 

 oxylon 1 , a term since applied by Solms-Laubach and other authors 

 to a certain type of cortex not confined to a single genus of plants, 

 occurs also in some Palaeozoic lycopodiaceous stems 2 and in itself 



FIG. 401. Lyginodendron Landsburgii. (Kidston Coll. f nat. size.) 



cannot be regarded as a safe criterion of botanical affinity. The 

 largest example of Gourlie's Lyginodendron that has come under 

 my notice is an incomplete sandstone cast from Upper Carboni- 

 ferous strata near Harrogate reaching a length of 100 cm. and 

 1 Solms-Laubach (91) A. pp. 8, 217, 218. 2 Vol. n. p. 220. 



