60 



Hud/on. On the Pillars of Roflyn Chapel near Edinburgh ; Dr. Smitfr. 

 On the Ruins of the Chapter Houfe at Margam, and the Walls of Oyfter- 

 mouth Caflle, Glamorgan ; Mr. Young. 



This fpecics, for the difcovery of which I am indebted to Mr. Young, fo 

 nearly accords with the defcription in the Hiftoria Mufcorum, that I feel 

 no hefita ion in publifhing it as the Byjfus leruginofa of Hudfcn. It is an 

 extremely minute fpecies, of a bluifh green color, and rather powdery 

 appearance. When examined with the higheft powers of the microfcope, 

 the filaments are feen to be twice or thrice dichotomous, and diflepiments 

 may be here and there obferved, dividing them into joints, whofe length 

 is about equal to three times their diameter. Mr. Young remarked that 

 the branches are fometimes fingularly reflected. On the termination of 

 each branch there are generally two oval bodies of a dark green color, 

 which I fuppofe are either capfules or naked feeds, but they are fo minute 

 that it is impoffible to fpeak with any certainty of their nature, and it is 

 thefe which give the plant its powdery appearance. 



The drawing at Plate D was made by Mr. Young, and reprefents the 

 plant both of its natural fize and when magnified with the higheft power 

 of a compound microfcope. 



79. ebenca. C. fills ramofis, ereftis, abbreviatis, cartilagineis, nigris ; ramis. 

 ramulifque obtufis ; articulis diametrum longitudine xquantibus. T. 101. 



80. atro-i'irens. C. filis ramofis, rigidiufculis, atro-virentibus ; ramis fub- 

 frcundis utrinque attenuatis'; articulis breviflimis tripun£latis. T. 25 and 

 T. D. 



Lichen exllis. Auctorum. 



The fructification- of this fpecies, which I difcovered on fome fpecimens 

 gathered near Be'ddgellart, is reprefented at plate D magnified 1. 

 81.* cccllata. C. filis ramofis, flaccidis, intra moniliformibus, fufcefcentibus ; 

 ramis fub-fecundis, remotis elongatis, fimplicibus; articulis diametro 

 tlimidio brevioribus, centra foepe notatis. T. D. 



