268 



DESCRIPTIVE CATALOGUE 



4-8 cells broad, and about 40-60 cell-rows higb ; numerous 

 narrower rays, about two cells broad, interspersed between the 

 broad ones. Much wood-parenchyma round the vessels and in 

 groups among the fibres, which are relatively few, thin-walled, 

 and with roundish bordered pits. Growth-rings, if present, 

 more than 2'5 cm. wide, which is the width of the specimen, in 

 which none are present. 



HORIZON. Lower Greensand. 



XOCA.LITX-. Woburn Sands, Bedfordshire. 



TYPE. Block V. 5452, and slides Y. 5452 a, 6, c, d, and e cut 

 from it in 11)11 ; British Museum (Nat. Hist.). 



Text-fig. 79. Wolwrnia porosa, Stopes. Purt of a transverse section, to 

 show the numerous large vessels and the broad wavy medullary rays. 

 X 10. After Stopes. 



GENERAL DESCRIPTION. The species is founded on a single 

 specimen, composed only of secondary wood. A wedge-shaped 

 piece, roughly 2-5 x 1*8 cm. in diameter, shows no signs of 

 growth-zones, but is quite uniform throughout. Externally the 

 woody texture is weathered out and recognisable to some extent, 

 and at one end the medullary rays and the vessels can be 

 detected in the weathered surface. On the cut surface the rays 

 and the vessels can be clearly seen with the naked eye. As can 



