1915] 



OVERHOLTS — STUDIES IN THE POLYPORACEAE 703 



a synonym for P. betulinus. In 1823 Hornemann 1 published 

 a figure of P. spumeus entirely different from Sowerby's 

 original figure, but in all probability a better representation 

 of his original species. It was not, however, so accepted at 

 the time. In the text accompanying the plates in 'Flora 

 Danica,' Hornemann refers to Sowerby's original figure as a 

 variety (var. stipitatus) of P. spumeus. This was evidently 

 only a makeshift to dispose of a troublesome figure, and since 

 the figure itself was evidently an error, Hornemann 's disposi- 

 tion of it need have no weight. Subsequent writers did not 

 concur in his opinion, however, and the confusion was only 

 made worse, for now some regarded that there were two dis- 

 tinct plants passing under the name of P. spumeus. In 

 Hooker's 'English Flora,' 2 in which the fungi were written 

 up by Berkeley, both Hornemann 's and Sowerby's illustra- 

 tions are cited as representing P. spumeus, and Hornemann 's 

 figure is given priority in the order of citation. Again the 

 plant is described as possessing an obsolete stipe and an in- 

 curved margin — characters either taken from Sowerby's il- 

 lustration or copied from Fries. That Berkeley was in doubt 

 as to the correctness of Sowerby's plate is evidenced by the 

 statement: ''According to Fries, the figure of Sowerby repre- 

 sents the species in an imperfect state " In 1874 



Fries 3 accepted Sowerby's figure as representing P. spumeus 

 and referred Hornemann 's figure to P. epileucus. This refer- 

 ence was evidently followed by Saccardo. Berkeley 4 pub- 

 lished an illustration of P. spumeus that corresponds well 

 with Hornemann 's figure and agrees with the plants since 

 referred to that species. Thus there has arisen an interesting 

 situation in which, according to the writer's interpretation, 

 a well-known species is referred to an erroneous illustration 

 that cannot possibly represent it, while the authentic illustra- 

 tration is referred to another species. Of course it is possible 

 that Hornemann may have misinterpreted Sowerby's P. 



1 Fl. Dan. pi 179^. 1823. 



a Eng. Fl. 5 2 : p. 139. 1836. 



"Hym. Eur. p. 552. 1874. 



'Outl. Brit. Fung. pi. 16. f. If. I860. 



