180 PLACODIUM. 



eating only an advance in the same direction of known condi- 

 tions of the vitellimtm-SQOTQ. Apothecia seen l mm - to i mm - ? 5 

 wide. Paraphyses becoming thickened and like the spores. The 

 last seen only in eights. 



25. P. crenulatum (Wahlenb.); thallus orbicular, crenate- 

 granulose, opake ; lemon-coloured ; radiately effigurate at the 

 circumference, the lobes crenate incised; apothecia of almost 

 middling size ; pale-lemon-coloured, bordered by a creuate thai- 

 line margin. Spores 20-40 and more in the thekes; ellipsoid 



and oblong, simple and obsoletely bilocular, ^jj- mic. Leca- 



nora crenata, Nyl. Lapp. Or. p. 130. Caloplaca cremilata, Tli. 

 Fr. Scand. p. 187. 



Maritime rocks, Greenland (Vahl), Th. Fries 1. c. 1861. 

 The only specimen known to me as yet by this name (Labrador, 

 Krempelhuber) might quite as easily be called a well-developed, 

 high-northern condition of the next species ; and little more is 

 suggested by Nylander's character of the lichen. Wahlenberg 

 however (Fl. Lapp. p. 416) describes his plant as having thin, 

 and exceedingly narrow (and Th. Fries adds sub-linear) lobes, 

 which suggests something different. 



26. P. vitellinum (Ehrh.), Naeg. & Hepp. ; thallus effuse, 

 tartareous, of small, rounded, at length squamaceous and cre- 

 nate-lobulate granules, which are crowded mostly into areole- 

 like heaps, but occur now scattered; bright-greenish-yellow; 

 apothecia clustered for the most part, middling to small, sessile, 

 flat, or at length convex; tawny-yellow, darkening also, and 

 olivaceous, with a soon granulate - crenate thalline border. 

 Spores numerous (12-30 and more) in the thekes; simple and 



bilocular, -^ mic. Fr, L. E. p. 162, excl b. Nyl Scand. 



p. 141. 



b. aurellum, Ach. ; thallus dispersed and disappearing ; the 

 small apothecia entire. 



Dead wood and rocks, common; as also occurring on the 

 earth. Northern and middle States, Muhlenberg Catal. 1818. 

 Arctic America (Fort Franklin), RicJiardson. Behring's Straits, 

 Wright. Illinois and westward, Hall. Rocky Mountains, Parry; 

 Hall. Texas, Wright. New Mexico, Fendler. California, Bolan- 



aer. b } on rocks, Canada, Mr. Drummond. Missouri and 



Kansas, possibly, Hall; but not clear. The spores of this 



