270 Rev. W. A. Leighton on the British Graphidese. 



Thallus thin^ membranous, smooth, very slightly shining, pale 

 yellow, limited by a brown wavy line, uplifted so as to form a 

 thin membranous spurious border to the lirellse. Lirellee nu- 

 merous, appi'oximate but not crowded, for the most part very 

 short and straight, arranged in somewhat of a subparallel man- 

 ner, with others longer and variously though slightly curved or 

 waved, interspersed and scattered, subsessile or a little raised 

 above the level of the membranous thallus, narrow, slender and 

 simple, one here and there with a single simple short branch at 

 right angles, the smaller ones generally pointed at both ends, 

 the larger ones of about the same width thi-oughout, and more 

 obtuse or obtusely pointed at the extremities. Disk rimaeform 

 or slightly channelled when dry, when wetted expanded and flat, 

 brown, with or without a very slight pruina, surrounded by a 

 tolerably thick, uniform, black, curved and wavy proper margin. 



/S. diffusa. Lirellse elongated, simple, curved, distantly scat- 

 tered in all directions. 



On ash. Charlton Forest, Sussex ! Mr. Borrer. On sycamore, 

 Derriquin, Ireland ! Dr. Taylor in herb. Borrer. On Ulmus mon- 

 tana, Colin Glen, Belfast ! Mr. W. Thompson. 



Thallus thin, slightly tartareous, continuous, even, or in irre- 

 gular rugosities, pale yellow or pale olive, elevated into more or 

 less stout and thick spurious margins about the lirellse, by abra- 

 sion probably, becoming there whiter and pulverulent, limited by 

 an irregular wavy brown line. Lirellee elongated and slender, 

 curved, wavy and distantly scattered in all directions, simple or 

 very seldom with a single short branch at right angles, not up- 

 raised above the level of the spurious margins, or only in a very 

 slight degree, of about the same width throughout, though here 

 and there a little contracted, obtuse or obtusely pointed at the 

 extremities. Disk rimseform when dry, when wetted expanded 

 and flat but still narrow, encompassed by a curved, wavy and 

 crisped narrow proper margin. 



The right-hand specimen of " No. 90. Opegrapha scripta, 

 B. abietina, Schaerer,'^ in Mr. Borrer^s copy of 1st ed. of Schserer's 

 * Lich. Exsicc.,^ and the left-hand specimen of No. 90 in my copy 

 of " edit. alt. immut.," apparently belong to this variety. 



7. varia. Lirellse elongated, very various in shape, size and 

 disposition, rather crowded. 



On young oak. Sussex ! Mr. Borrer. On alder, near Little 

 Malvern, Worcestershire ! Mr. E. Lees. 



Thallus thin, membranous, continuous, minutely tuberculate, 

 or nearly smooth and scaly, pale yellow or pale olive, upraised 

 and forming a distinct tumid narrow spurious margin to the 



