Ill] 



PSILOPHYTON 



17 



authority i:esident in America where the type specimens of 

 Dawson are located. 



According to modern opinion, Dawson^ in 1871 included at 

 least two species under the term P. princeps. Confusion has also 

 arisen from the attribution by Carruthers^ in 1873 of some of 

 the Scottish examples to Goeppert's Haliserites Dechianus, as 



Fig. 3. Psilophyton princeps, Dawson. Type 

 specimens of Dawson's variety " ornatum,^'' 

 with macroscopic emergences. Tlie left-hand 

 figure sliows the circinate vernation. After 

 Dawson (1871). 



P. Dechianum (Goepp.). In fact at the present time the Scottish 

 plant is probably better known under that name than by any 

 other. These difficulties may be overcome as follows. Carruthers' 

 determination should be completely ignored. In our opinion it 

 is erroneous. Further the specimens which he figiu'cs do not 

 belong to Psilophyton at all, but to a distinct genus Ptilophyton. 



1 Dawson (1871). 



Carrutliers (1873). 



