A NEW MEDULLOSEAN STEM. 



101 



metaxylem elements typically witli biseriate bordered pits. Medullary rays uuiseriate. 

 Ground-tissue parencliymatous, with scattered and irregular vascular strands, bands of 

 periderm, and sclerotic nests. 



H. AFRTCANTJM, nOV. Sp. 



Characters of the genus 



(2) The general structure of Mhexoxylon africcmum suggests relationship with the 

 genera Medullosa and Stelowylon, and the new genus is included in the family 



Medullosese. 



In conclusion, the writer's expressions of gratitude are due to Professor Seward 

 for help and advice during the above investigation; and also to Dr. 11. Kidston for 

 slides of Cladoxylon Kidstoni which he kindly lent for comparison with the South 

 African stem. 



Botany School, Cambridge. 



Ueferences. 



(0 



SutcliM 



Specimen. Ann, of Bot. vol. xxvi. 1912. 



(2) 



Die Medulloseee. eine neue Gruppe der fossilen Cycadeen. 



Palseontographica^ 1881. 



(3) 



(4) 



Myehxylon. New Phyt. vol. ix. 1910. 



mien d'Autun et d'Epinac. Flore Fossile, iv. pt. II. 1896. 



(5) Rogers, A. W., and Du Toit, A. L.— An Introduction to the Geology o£ Cape Colony. 1909. 



(6) ScHENK, A.— Ueber Medullosa 



Abhandl. der math. phys. CI, der k. 



Sachs. Gesellschaft der Wissenschaften, vol. xv. no. vi. 1889. 



(7) Scott, D. H.— Structure and Affinities of Fossil Plants from the Palaeozoic Rocks. III. On 



Medullosa anglica, a new Representative of the Cycadofilices. Phil. Trans, Roy. See. B, 



vol. cxci. 1899. 



(8) On Sulclifa insignis, a new Type of Medullosese 



Linn. Soc. vol. vii. p. 45. 1906. 

 (g) Studies in Fossil Botany. 1909. 



Trans. 



(10) Solms-Laubach, H. Graf zu.— Ueber die Seinerzeit von Unger beschriebenen structurbietenden 



Pflanzenreste des Unterculm von Saalfeld in Thuringen. Abhandl. der k. pr. gcologischen 



Landesanstalt, Neue Folge, lief t 23. 189G. 



(11) JJeher Medullosa Leuckarii. Bot. Zeit. vol. Iv. p. 175. 1897. 



(i2j . Ueber die in den Kalksteinen des Culm von Glatzisch-Falkenberg in Schlesien erhaltenen 



structurbietenden Pflanzenreste. IN .— Volkelia refractay Steloxylon Ludwigii. Zeitschrift 



fur Botauik, 1910. 



(13) Weber, O., and Stebzel, J. T 



zu Chemnitz, vol. xiii. 1896. 



(14) WoRSDELL, W. C— The Structure 



p. 129. 1906. 



zur Kenntniss der MeduUoseae. Ber. der Naturw 



of 



