28 FUNGUS-FLOKA. 



Eeadily distinguished by the oyster-shaped ascophore, and 

 the very large, coloured, muriform spores. 



Ostreion americanum. Duby, Hyst., p. 22, t. 1, 

 fig. 1 ; Sacc., SylL, n. 5715. (fig, 31, p. 22.) 



Ascophores scattered, oyster-shaped, black, rather shining, 

 indistinctly transversely striate, slit narrow, edge obtuse, 

 2 mm. long ; asci cylindrical, narrowed at the base; apex 

 obtuse, 4-spored, rarely containing 3 or 5 spores ; wall rather 

 thin ; spores elongato-fusoid, ends rather acute, slightly con- 

 stricted at the middle, niultiseptate and muriform, dark 

 brown and almost opaque at maturity, a minute cell at each 

 end paler, 90-110 X 25-28 //.; paraphyses numerous, very 

 slender, about 1 J fx thick, everywhere equal, much branched, 

 hyaline, flexuous. 



On bark. 



The ascophore is usually straight, but sometimes slightly 

 curved, or even showing an approach to a triradiate arrange- 

 ment of the slit. Very brittle and carbonaceous. 



An American specimen from Curtis examined, with which 

 British specimens exactly agree. 



HYSTEROGRAPHIUM. Corda, (figs. 32-33, p. 22.) 



Ascophore erumpent or superficial, sessile, black, firm and 

 rigid, dehiscing by a longitudinal slit, lips obtuse; asci 

 clavate, 8-spored ; spores biseriate, smooth, 3-multiseptate 

 then muriform, brown or olivaceous ; paraphyses present. 



HysterograpMum, Corda, Icon., v. p. 34 (in part) ; Sacc, 

 SylL, ii. p. 776. 



Hysterium, of some authors. 



Differs from Ghniojpsis, its nearest ally, in having coloured 

 spores. 



* Spores b- septate. 



Hysterographium Rousselii. Sacc, SylL, ii. n. 5768 ; 

 Rehm, Krypt.-Flora, Hyst., p. 21. 



Ascophore erumpent, sessile, black, linear-oblong, generally 

 gregarious and arranged in parallel series, depressed, straight 

 or very slightly bent, 1-3 mm. long, |— 1 mm. broad r lips 



