292 GEOLOGY OF THE ISLE OF WIGHT. 



have been detected in the carboniferous strata ; 

 and in the Lias and Oolite they appear in immense 

 numbers; several species have been found in 

 the Wealden, and cretaceous formations. The 

 discovery of cones of a species of Zamia (Z. crassa, 

 "Medals of Creation," p. 160), associated with 

 bones of the iguanodon, in the Wealden strata in 

 Sandown Bay, has already been mentioned (p. 138). 



Clathraria Lyellii. — But the most interest- 

 ing fossil plant belonging to this tribe of coniferae, 

 of which any remains have been found in the 

 Wealden, is that discovered by me in Sussex, and 

 described in 1822; and subsequently in "The 

 Fossils of Tilgate Forest," under the name of 

 Clathraria Lyellii. * 



This plant was formerly classed with the Lilia- 

 cew, by that eminent botanist M. Adolphe Brong- 

 niart ; but the discovery of more illustrative 

 specimens than those first obtained, indicate its 

 affinity to theCycadeae, with which M. Brongniart 

 has some years since arranged it. The stem of the 

 Clathrariaf is composed of an axis having the sur- 

 face covered with reticulated fibres, and of a false 

 bark produced by the union of the consolidated 



* Fossils of Tilgate Forest, Plates I. M. III., and doin-y of tin- South 

 East of England, PI. I. 



I Clathraria, or latticed stem ; so named from the scorings left on the stem 

 by the • thi petioles. 



