268 RoccELLA TiNCTORiA AND R. PHYCOPSis. [September, 



seems to be only a variety of R. fuciformis, and almost interme- 

 diate between it and R. tinctoria." I can see no similarity what- 

 ever in the form Phycopsis to R. fuciformis. It is unquestionably 

 a variety only of R. tinctoria. These two forms grow intermixed 

 both in Guernsey and the Isle of Wight. Fries^ as I think, cor- 

 rectly makes only two Roccellas, tinctoria and fuciformis, but 

 Acharius and Schserer both admit R. Phycopsis as a distinct spe- 

 cies. I have not Acharius's work by me to refer to, but in the 

 description of the two plants by Schserer I cannot see sufficient 

 grounds for keeping them distinct. He describes R. tinctoria as 

 having the thallus "teres, tandem nodulosus;" R. Phycopsis as 

 having the thallus " tereti-compressus subangulosusque." Now 

 all the filamentous Lichens vary so much in the comparative 

 roundness and occasional flatness of the thallus, that I cannot 

 consider the above characters as sufficient to keep them distinct. 

 Again, he says of R. tinctoria, " rarius simplicibus vel bifurcatis ;" 

 of R. Phycopsis, " rarius simplicibus vel dichotomis." Here the 

 only distinction is between bifurcatis and dichotomis, and what 

 that distinction is I am unable to discover. Then with respect 

 to the soredia, the only distinction he gives is that in R. Phycopsis 

 these are " frequentissimis, ssepe agglomeratis.^^ But in the Par- 

 melice and other sorediiferous Lichens we do not consider the 

 greater or lesser abundance of soredia as a distinctive character. 

 The chief distinctions between these two forms of Roccella is that 

 expressed in fact in the name itself, " Phycopsis," which I ima- 

 gine was formed from (J)vko<; and oT/rt?, ' having the appearance of 

 the Bladder Seaweed,' the form Phycopsis having, in fact, swel- 

 lings here and there upon its frond. 



Though I cannot consider that R. tinctoria and R. Phycopsis 

 are any more than varieties ot the same plant, it is at all events 

 interesting to know that we have the form Phycopsis growing 

 in the Isle of Wight. I would only add that some of the plants 

 from St. Helen's, and especially the one from Shanklin church, 

 are identical with a specimen I have of R. Phycopsis from the 

 herbarium of Delisse, given to me by my friend Mr. Ralfe, of 

 Penzance. 



Worthing, July \Ztli, 1860. 



