30 Rev. T. Salwey^s List of Lichens in Wales. 



Collema Burgessii. "Woods about Barmouth and Dolgelley, Garth, 

 Crafnant, &c. 



nigrescens. Common, but usually barren ; very finely in fruit 



upon trees at Stackpole Court in Pembrokeshire. 



There is a large spreading foliaceous Collema, of a looser habit and 



of a dull tawny green colour, found not uncommonly in the woods in 



Wales, and has been gathered also by Mr. Borrer in Sussex. Dr. 



Taylor refers it to nigrescens, but it is very different from the usual 



state of that plant. 



Jlaccidum. Common upon wet rocks and trees, but barren. 



crispum. Common. 



dermatinum. On limestone rocks at Stackpole Court, Pem- 

 brokeshire. 



— tremelloides . On wet rocks above the Tannery, and above 



the Harlech turnpike-gate at Barmouth, but not in fruit. 



lacerum. In fruit at Garth Issa. 



myriococciim. I have a single specimen of this plant ga- 



thered on the limestone rocks at Lydstep in Pembrokeshire. 



velutinum, Ach. Occasionally met with on trees. Dr. Taylor 



refers this to nigrum. 



ceranoides. Rocks at Tenby and Lydstep, Pembrokeshire. 



muscicola. Common, but not in fruit. 



Solorina saccata. Clogwyn-y-Garnedd, Snowdon. 



Peltidea venosa. By the side of a brook on the Glyder Vawr, Mr. Ralfs. 



I consider this as distinct from spuria. 



scutata. In fruit at Cors-y-gedol, &c. 



horizontalis. Not uncommon. 



aphthosa. Very finely amongst the stones by the borders of 



lakes, as Llyn Bodlyu, &c. 

 spuria. Ynysfaig. 



It is stated by Hooker in the ' Eng. Fl.' that rvfescens scarcely 

 differs except in hue from spuria, whilst he says of this (spuria) that 

 it appears as distinct as any. Acharius, who in his ' Lich. Un.' had 

 made spuria a variety of canina, has in his ' Syn.' united these two. 

 Dr. Taylor, a high authority on such points, has done the same ; and 

 I am inclined to agree with them that spuria is only a starved and 

 diminutive state of canina ; but I cannot persuade myself that rnfes- 

 cens and canina are the same. Dillenius (103. xxvii. p. 203, Edinb. 

 ed. 1811) makes rufescens to differ from canina, principally in the 

 following particulars : — 



1st. In the thallus being somewhat thicker, more rigid and smaller ; 

 in being divided into narrower and deeper segments ; and in the mar- 

 gins being inflexed, sinuated and crisp. 



2ndly. In the colour, which in rufescens is darker, and when dry 

 is reddish, 



Srdly. In the under part of the thallus being more villous, and 

 with blacker, shorter and more curled roots. Dillenius speaks of ru- 

 fescens also as being more common than canina, which corresponds 

 also with my own experience. 

 Gyrophora polyphylla. Common. 



