290 GEOLOGY OF THE ISLE OF WIGHT. 



not the vessels themselves, but the hollows left by 

 their decay.* The occurrence of this fossil plant 

 in the Wealden of the Isle of Wight has only 

 recently been discovered. Among the waterworn 

 fossils which I collected from the shingle, on my 

 last visit to Brook Point, was a rounded, sub- 

 cylindrical block of sandstone, very smooth, and 

 marked externally with small crescent -shaped 

 spots, which are the terminations of bundles of 

 vascular tissue. 



A transverse section of this fossil proved it to be 

 a portion of the stem of the Endogenites erosa, in a 

 better state of preservation than any example pre- 

 viously obtained. The openings, instead of being 

 empty, are for the most part occupied by the vessels ; 

 and an external band, or zone, of vascular tissue, 

 disposed somewhat in festoons, is tolerably well 

 preserved. Very thin slices, immersed in Canada 

 balsam, to render them as transparent as the dull 

 siliceous substance of which they are composed 

 will admit of, examined under the microscope, 

 indicate, in the opinion of Dr. Robert Brown, a 

 nearer approach to the Cycadeae than to the Endo- 

 genous tribes. 



Fossil cycadeous plants. — Among the coni- 

 ferae, or cone-bearing plants, the Cycadecc and 



" Dr. FittOI) has given magnified figures of the sections in Ills pi, xx. 



