116 DESCRIPTIVE CATALOGUE 



certain that the three slides represent the same specimen. As 

 it is unproved, however, they cannot be diagnosed. 



Pityoxylon Woodward!, sp. nov. 

 [Plates VIIF, IX; text-figs. 28, 29.] 



Diagnosis. Secondary wood with the characters of Pitt/- 

 oxi/lon, Kr. The type is part of a trunk which, judging by the 

 curvature of the rings, must have been of some considerable size. 

 Growth-rings very well marked, the walls very much thickened. 

 Tracheids of spring wood large, 50 x 65 yu, up to 90 /t in dia- 

 meter, with large, round, bordered pits, or " twin-pits," or pits in 

 pairs on the radial walls. Tangential pits in autumn wood. 

 Wood-parenchyma in quantity between the resin-canals. Kcsiri- 

 canals exceedingly numerous and conspicuous, in all the growth- 

 rings, in tangential bands alternating in adjacent rings; all in 

 autumn wood. llesin -canals large, *2-*3 mm. in diameter, 

 epithelium apparently thin-walled. Medullary rays conspi- 

 cuous, cells differentiated. " Abietinean pitting'' seldom visible. 

 Radial walls with a single, large, very narrowly bordered pit per 

 tracheid-field, ray-tracheids irregular in outline, smooth-walled, 

 with small, round, bordered pits. 



HORI/ON. Lower Greensand. 



LOCALITY". Woburn, Bedfordshire. 



TYPE. V. 5429 and sections cut from it; British Museum 

 (Nat. Hist.). 



I ? IXDKR. H. Veasey, Esq., before 18!)>. 



DESCRIPTION. This species is represented by a Hat wedge- 

 shaped specimen of secondary wood, I*5x3'5cra., and about 

 20 cm. long, evidently part of a large trunk. The external 

 surface is much weathered, and the end is rounded off by water- 

 wear, apparently before it was petrified. The petrifaction is 

 irregular, the inner portions being dark brown in colour. 



TOPOGRAPHY OF THE STEM. Secondary wood only is preserved, 

 and in this the growth-rings are very well marked. The 

 elements composing a ring number in radial scries from about 

 35 to 70, the maximum thickness being about 2'5 mm. The 

 autumn wood is about half the total thickness of the ring, and 

 consists of extremely thickened and stony cells; even the first 

 elements of spring wood have thickened walls. Rows of large 



