HYSTERIUM OSTKEION. 27 



than the two middle ones, also a little smaller, 24-30 x 7-9 p. ; 

 paraphyses slender, branched and tinted with olive at the 

 apex. 



On the bark of various trees, oak, chestnut, walnut, birch, 

 poplar, &c. 



Specimen examined from Fries' Sclerom. Suec., n. 61. 



The spores are somewhat variable, the most general and 

 typical form being the one described above. Sometimes all 

 four cells of the spores are coloured dark brown, sometimes 

 three only, one end-cell alone remaining paler. Sometimes 

 1 septum only is present at maturity, sometimes 2 ; in very 

 rare cases 4 septa are present. 



Hysterium angustatum. A. & S., Consp. Fung. 

 Nisk., p. 55; Cke., Hdbk., p. 758; Sacc., Svll., n. 5636; 

 Kehm, Krypt.-Flora, Hyst., p. 14. 



Ascophores gregarious or crowded, often parallel, at first 

 partly immersed, then superficial, sessile, elliptical, some- 

 times very short and almost round, straight or slightly 

 curved, almost smooth, black, opaque, slit closed, 1-3 mm. 

 long, ^ ^ mm. broad ; asci clavate, wall thick upwards, 

 8-spored ; spores elongated elliptical, ends rounded, 3-septate, 

 rarely more, pale brown at maturity, smooth, cells usually 

 1-guttulate, 17-25 X 6-7 //.; paraphyses slender, branched 

 above. 



On the bark of various trees, as oak, birch, &c. 



H. pulicare superficially resembles the present species, but 

 is distinguished by the two end-cells of the spores being 

 paler in colour than the central ones. 



Specimen in Eehm's Ascom., n. 214, examined. 



OSTEEION. Duby. (fig. 31, p. 22.) 



Ascophore superficial, oyster-shaped, rather narrowed at 

 the base or substipitate, vertical, laterally more or less com- 

 pressed, black, dehiscing by a narrow, elongated slit, carbo- 

 naceous ; asci subcylindrical, usually 4-spored ; spores very 

 large, elongated, coloured, multiseptate and muriform; para- 

 physes present. 



Ostreion, Duby, Hyst., p. 21 (incorrectly written Ostreich- 

 nion) ; Sacc., Syll., ii. p. 765. 



