io4 



STUDIES IN FOSSIL BOTANY 



with S. cuneifolium. In the smaller form (ft) there is 

 a slender, triarch xylem. 



Fig. 43. — Sphenoj>hyllum Dawsoni, a. Obliquely transverse section of cone, showing 

 parts of three whorls of bracts. a", hollow axis (stele missing) ; b, d, cortex of axis ; 

 £, e', bracts cut at different levels ; f, sporangiophores, the innermost just springing 

 from a whorl of bracts, which are here coherent ; /', sporangiophores in connection 

 with their sporangia ; g, g> g", sporangia of the three whorls, x 7. After Williamson, 

 Phil. Trans. Will. Coll. 1049 B. 



