OF LOWER GREENSAND PLANTS. 91 



V. 4859 g. Figured, text-fig. 19. A further radial section of 

 the above, part of which slopes obliquely into a tan- 

 gential direction. In one place a resin-canal is cut 

 obliquely and shows the thick and pitted walls of ils 

 lining very clearly, as is illustrated in the text-figure. 



V. 4859 h, j, k. Further radial and obliquely tangential sections 

 of the above, in which many of the described features 

 can be seen. 



V. 4859 1. Figured, text-fig. 22. Tangential longitudinal section 

 showing the rays and also the longitudinally running 

 resin-canals very beautifully. 



V. 4859 m. A tangential section similar to the above, but rather 

 thicker and somewhat oblique. 



Lower Greensand ; Berwick Greer, Sussex. 



Transferred from the Botanical Dept., 1898. 



Genus PITYOXYLON, Kraus. 

 [In Schimper's Traite Pal. Yege't., vol. 2, 1870, p. 377.] 



The species of woods which Witham and, later, Kraus him- 

 self (see Kraus, 1864, 1866) described under the generic name 

 Pinites, were placed in 1870 in a genus of equivalent value to 

 those of other fossil woods, with the characteristic termination 

 -oxylon. In Schimper's textbook, where the new generic name 

 Pityoxylon is first used, Kraus defines it as follows : " Lignum 

 stratis concentricis angustis, latioribusve ; cellulis prosenchy- 

 matosis porosis ; poris magnis, rotundis, uni- vel pluriserialibus, 

 oppositis ; cellulis ductibusque resiniferis baud raris ; radiis 

 medullaribus compositis ductumque resiniferum includentibus 

 vel simplicibus, cellules eorum haud raro biformes." To this 

 Kraus adds : " Le genre Pityoxylon est le seul dans lequel il 

 soit possible d'etablir des sous-divisions et des especes sur les 

 differences de structure qui se rencontrent dans le tissu. Les 

 caracteres distinctifs se trouvent en partie dans la disposition 

 des canaux resineux, en partie et surtout dans 1'organisation des 

 cellules qui composent les series iuferieures et superieures des 

 rayons medullaires." Beyond these words he does not give any 

 description, or even reference, to the cells of the medullary 



