ROOM I. 



CLATHRARIA. 



47 



traces of structure ; and in those which retain some vestiges of 

 organization, the siliceous mass into which the vascular tissue 

 is transmuted, is not sufficiently transparent to yield satis- 

 factory results ; it can only be inferred that in their internal 

 organization, as in their external characters, the Clathrarise 

 were most nearly allied to the Cycadeae or Zamise. A remark- 



LTGN. 16. CLATHKARIA LYELLII. CHALK MARL. 1 

 (J not. size.) 



The summit of a stem garnished with petioles; the lower part shows the cicatrices 

 left by the removal of some of the petioles : a, the internal axis. 



able specimen discovered in a stratum of chalk marl near 

 Bonchurch, in the Isle of Wight, throws much light on 

 these interesting plants : and I insert a figure, to illustrate 

 the fossils in the case before us. It consists of the summit 



This specimen is in the collection of Captain Ibbetson, F.R S. 



