296 STUDIES IN FOSSIL BOTANY 



disposition of their leaves may have been, are embraced 

 under the common name Psaronius. We have thus a 

 curious example of palseontological nomenclature, for 

 one and the same stem, according to its mode of 

 preservation, may be placed in any one of the three 

 " genera," Caulopteris (or Megaphytum, as the case may 

 be), Ptychopteris, or Psaronius. If the foliage and 

 fructification were taken into account, still other generic 

 designations would come into requisition. Yet these 

 anomalies are unavoidable, for it is rarely possible to 

 identify the same species through its different states 

 of fossilisation. 



For our present purpose, the name Psaronius is the 

 most suitable, as it is with the anatomical structure of 

 the stem that we are specially concerned. 



The specimens of Psaronius, which are characteristic 

 fossils in the Permian beds of Saxony and Central 

 France, were perhaps the earliest known of any fossil 

 vegetable remains with structure preserved. They 

 were quite familiar objects, even to the general public, 

 in the eighteenth century, for, owing to the beauty of 

 their surface when cut and polished, they became, for a 

 time, favourite articles of ornament, under the name of 

 " Staarsteine." 1 The markings, to which they owed 

 their popularity, depend on their anatomical structure. 



The genus contains a great number of described 

 species, and though some may have merely a palaeonto- 

 logical value, many no doubt represent real distinctions 

 among the plants when living. The species from the 

 Upper Coal-measures and Permian agree in having a 



1 " Starling-stones," from the speckled surface. The technical name 

 Psaronhis has the same origin. 



