EOSSIL FLOKA. 33 



PLATE VIII. 



Petrified Stems and Woods. 



Figs. I — 7, represent diflferent sections and parts of some remarkably beautiful and interesting 

 siliclfied stems of an extinct tribe of plants, related to the arborescent ferns, and 

 which are found in considerable abundance at Chemnitz, near HUiersdorf, in 

 Saxony. The name of Psaronius is given to the genus by M. Cotta. 



Figs. 1, 2, 5, 7, are P. helminth olithes; figs. 3, 6, P. asteroUthes ; figs. 5, 6, 7, are enlarged figures 

 of the transverse sections of some of the vessels forming the vascular tissue. 



From the stellular figure produced by transverse sections of the vessels, this fossil wood has 

 received the name of ^' Staarenstein," or Starry-stone. In the time of Mr. Parkinson, the 

 tubes now known to be the vessels of the vascular tissue, were supposed to have been 

 produced by some boring or parasitical animals. 



Fig, 4. Transverse section of a stem of calcareous wood from the Bath oolite. 



Figs. 8, & 9. Calcareous fossil wood; the cylindrical cavities have been formed by the depre- 

 dations of the ligniverous boring mollusk, the Teredo, and are now filled with 

 translucent calcareous spar. This kind of fossil was called " Lapis syriiigoides" 

 by the early collectors. 



FIg. 10. Silicified wood ; the perforations are supposed to have been occasioned by the 

 depredations of boring mollusca: the cavities are filled with a white pellucid 

 chalcedony. 



