130 Rev. W. A. Leigh ton on new British Lichens. 



peculiar structure of the perithecium and sporidia of that plant, 

 at once separate them. 



Dr. Nylander, in his " Nouv. Classif. des Lichens/' mem. 2, 

 in tome iii. Mem. Soc. Sc. Nat. Cherbourg, gives as chemical 

 distinctions between the genera Graphis and Opegrapha, as 

 arranged by him, the following : viz. Graphis : " sporse iodo 

 cserulee infuscatse, eodem vero gelatinam hymeneam non colo- 

 rante." Opegrapha : " sporse iodo non tinctse, gelatina vero 

 hymenea ab eodem cserulee vel plerumque vinose-rubro colorata.^' 



The present plant is in fact a true Opegrapha with an entire 

 perithecium, and not a Graphis with a dimidiate perithecium ; 

 but as it partakes of Dr. Nylatider^s chemical character of Gra- 

 phis, and has at the same time the sporidia similar to those of 

 my G. scripta, I have named it on those accounts Opegrapha 

 anomala. 



We are indebted to the research of Mr. Horatio Piggot of 

 Chelmsford, Essex, for this interesting addition to our flora. 



Plate VIIL fig. 1. Opeg. anomala, nat. size. Fig. 2. Same, magnified. 

 Fig. 3. Vertical section of apothecium. Fig. 4. Ascus and spo- 

 ridia. Fig. 5. Sporidia, highly magnified. Fig. 6. Spermatia. 

 Fig. 26. Scale of magnitude for figs, b h Q. 



Coniocyhe citrina, Leight. Thallus leproso-pulverulent, citrine; 

 apothecia globose, yellowish-brown; stipes rusty-brown, pulve- 

 rulent, short and stout; sporidia minute, linear-oblong, uni- 

 septate, brown. 



On the under surface of stones in the walls of the turnpike 

 road between Corwen and Bala, North Wales, 4th June, 1856. 



Thallus pulverulent, of a pale citrine colour, spreading inde- 

 terminately to a considerable extent, of greater or less thickness, 

 either a mere sprinkling of dust, or else massed together in 

 moderate thickness, and then broken up by cracks into irregular 

 areolae. Apothecia scattered, singly, or in groups of several 

 together, stipitate. Stipes about J of an inch or more high, 

 nearly equal in thickness throughout, rusty-brown and pul- 

 verulent, bearing a small cup-shaped portion at the summit, 

 which speedily becomes obliterated by the expansion on all sides 

 of the round pulverulent mass of yellowish-brown sporidia, and 

 the remains of the asci and paraphyses. I could not detect 

 either asci or paraphyses, probably from the mature state of the 

 apothecia. Sporidia minute, linear-oblong, uniseptate, pale 

 brown. The septum is not always to be detected, and then the 

 sporidia appear simple or entire ; but I presume the septate 

 condition is the normal one. 



On the thallus occurred those minute plano-convex immargi- 

 nate waxy-looking bodies which lichenists have been accustomed 

 to regard as the apothecia of Biatora lucida, Fries (see Plate VIII. 

 figs. 10 & 11). With all the careful manipulation in dissection 



