OF LOWER GREENSAXD PLANTS. 03 



even though my new forms of Pityoxylon are certainly very 

 Pinus-like (see also pp. 102, etc.). 



It is curious that, though Pinus-like cones and foliage are 

 common, petrifactions of wood-structure like that of modern 

 Pinus are relatively rare, and, further, that, even in the deposits 

 in which they do occur, they are much more infrequent than the 

 other types of coniferous wood. For instance, Vater (1884, 

 p. 821) mentions that in a collection (probably so recent as 

 Senonian age) of about 250 specimens of petrified wood, only 

 four were of Pityoccylon. 



For comparison with our new fossils, therefore, there are not 

 many already-described forms, and indeed there appear to be 

 none which are of the same or very nearly allied species. In 

 the most recent work on the Lower Cretaceous of America 

 (Berry, 1911), unfortunately no species of Pityoxylon are 

 described. The species of Pityoxylon which are described 

 from Staten Island (Jeffrey & Chrysler, 1906, Bailey, 1911, 

 and others), and referred to by some botanists as of " Lower 

 Cretaceous " age, really belong to the Upper Cretaceous, and are 

 therefore much younger than those in the present work. Com- 

 parison with their structure, however, is made in detail (see 

 pp. 102, 120). 



The only British specimen of Lower Cretaceous (Wealden) 

 age, Pinites Rttffbrdi, Seward, 1S96 c, is not near our fossil in 

 its structure ; of this he says it " may possibly be generically 

 identical with the recent Pinus" but because of the absence of 

 leaves or cones he gives it the non-committal name of Pinites. 

 The pitting and the existence of both vertical and horizontal 

 resin -canals in the wood place the specimen in the genus Pity- 

 oxylon, Kraus ; but the fact that no horizontal ray-tracheids 

 have been detected appears to me to render any close affinity 

 with modern Pinus unlikely. The medullary ray-cells are 

 uniform, with straight walls and simple oval or circular pits, 

 generally two to each tracheid-field. This wood, without ray- 

 tracheids, is not much like our new species, and does not appear 

 to be so near to Pinus as was at first supposed by Seward. 



The three species of Pityoocylon nearest in age and geo- 

 graphical distribution to our Lower Greensand species, are 

 those described by Fliche (1896) from the French greeusands 

 of Albian age. They cannot be compared with the new species, 



