266 



Afitediluvian Zoology and Botany, 



Wood, properly so called, is more or less abundant in the 

 higher secondary strata. In none are they of mere interest- 

 ing character than in the Portland limestone, where enormous 

 silicified trunks are frequently discovered. Woody stems of 

 dicotyledonous trees appear in the lias. The tertiary beds 

 contain trunks and branches of trees, which are perforated by 

 the Teredo antenautae (Fistulana personata). In the London 

 clay so extensively have their ravages prevailed, that it is rare 

 to find any fossil wood free from them, and numerous instances 

 are observed where the original mass has been almost entirely 

 occupied by congeries of these animals. Fossil wood, perforated 

 by the genus Pholas, has been discovered in the ferruginous or 

 lower green sand. 



Leaves and fragments of arborescent plants occur in the 

 calcareous laminated sandstones near Hastings, and also in 

 Tilgate Forest. They form a species of coal, or Surturbrand, 

 in the plastic clay beds at Alum Bay, at Newhaven, and Corfe 

 Castle. 



Fruit and seed-vessels occur in the Yorkshire oolitic coal 

 shales, and abundantly in the London clay at Sheppy ; but the 

 number of species has been there greatly exaggerated, owing 

 to the fancied resemblance which some of the pyritous con- 

 cretions bear to organic forms. Those of undoubted vegetable 

 and terrestrial origin are, however, extremely abundant, and 

 appear to be closely allied to genera now existing in tropical 

 regions. Seven hundred species are said to have been col- 

 lected, by one individual, from the beach at the foot of Sheppy 

 cliffs. On careful examination this number will be found 

 exceedingly over-rated, and it may probably be reduced to 

 about twenty species. (,fig. 52.) 



Seed-vessels from Sheppy of the natural size. 



