LINDSAY, ON ABROTHALLUS. 47 



observations of Tulasne^ ^rlio says of the tliecse of A. Smithn, 

 " In iode soluto immersi nonnisi apice et dilute, quandoque 

 etiam vix conspicue coerulcseuut :" of those of ^. Welwitsschii, 

 " nee nisi dilutissime in iode sohito cferulescmit :" while 

 those of ^. microspermus consist of a '^membrana crassa qua 

 faljricantur in iode soluto tantum sordide fiavescit eodem 

 soil, niodo ac sporse." 



In all the varieties which I have examined the spores had 

 essentially the same characters. As measured by an eye- 

 piece micrometer, made by Bryson of Edinburgh, they gene- 

 rally varied in length from j-iVt ^o tjoo inch, and in 

 breadth from ^J^^ to ^j'^o '• sometimes, however, they were 

 larger ; at other times smaller. In general appearance they 

 resembled the spores of Physcia ciliaris, and some of the 

 Calicia ; and they appeared intermediate in size between 

 them. Korber describes them as shoe-sole-shaped {" schuh- 

 sohlenfdrmig'^), which, though rather an awkward designa- 

 tion, conveys a very true idea of their appearance. In many 

 cases there was little distinction in size between the loculi : 

 these v>xre chiefly young spores. The spores were gene- 

 rally olive-green — seldom of a deep brown. The latter tint 

 I have observed only in a few instances — as in specimens of 

 var. a from Ben Lawers, the A. Welwitzschii of Leighton's 

 'Lich. Brit, exsicc.' &c.. The spores of the Ben Lawers 

 specimens were dark umber-coloured, and broader than any 

 I have as yet seen : they had somewhat the appearance of a 

 figui'e of 8, and closely resembled on a smaU scale the spores 

 of P. ciliaris. Tulasne describes the spores of A. Smithii as 

 ^' atrae v. spisse fuscee;'^ those of ^. Welwitzschii as ^^ satu- 

 rate fuscae ;" and those of A. microspermus as " vulgo 

 pallidse." I would suggest that the dark colour of the spores 

 observed by him may be due to his lia^dng examined chiefly 

 herbarium specimens. Iodine seems to have no reaction on 

 the spores of A. Smithii or A. oxysporus. Tulasne allows a 

 similarity in the characters of the spores between his A. 

 Smithii and A. Welwitzschii ; for he says of the latter, " ab 

 illis ejusdem lichenis forma crassitudineque non differunt.'' 

 Of A. microspermus, he remarks : " Speciei criterium in 

 seminum utriusque generis exiguitate preesertim ponitur." 

 The paleness and minute size of the spores here constitute a 

 peculiarity ; but they do not appear sufficient to form specific 

 differential characters. Korber remarks : " Die Unterschiede 

 von der vorigen Art (A. Smithii) sind nur gering, so 

 dass sie ^delleicht besser als Varietiit zu dieser zu bringen ist " 

 (p. 216). Tulasne gives, as the habitat of this species, 

 Parmelia caperata. Korber says P. caperata with A. micro- 



