18 FUNGUS-FLORA. 



green liealthy appearance, and are covered on the under 

 surface witli a greyish-white hoariness, due to the presence of 

 the numerous asci, which are somewhat clavate, 46-60 x 15 /a, 

 stem-cell 16-17 /a long, 15 fx broad, tapering downwards and 

 penetrating between the epidermal cells; spores 3-4 /x, 

 diameter. 



Exoascus turgidus, Sadebeck, Krypt.-Mora, Gj-mno., p. 8; 

 Sacc, Syll., viii., n. 3347. 



Taphrina hetulina, Eostr., Bot. Centralbl., xv., p. 149. 



On Betula alba. Spring and summer. 



The " birds' nests " or " witches' besoms," so common on 

 the birch, are caused by this fungus. 



Excluded species. 



Ascomyces juglandis. Berk., Outl., p. 376; Phil., Brit. Disc, 

 p. 404. 



Ascomyces trientalis,'Ber^., in Cooke's Hdbk., n. 2234; Phil., 

 Brit. Disc, p. 405. 



The very brief descriptions appended to the above species 

 are absolutely valueless, and no type specimens exist, hence 

 the names must drop, because even if a species of Ascomyces 

 did actually occur on leaves of walnut or Trientalis, there 

 would not be the slightest proof that it was the species 

 intended by Berkeley. 



Subfam. II. GYMNOASCEAE. 

 GYMNOASCUS. Baran. (fig. 45, p. 12.) 



Ascophore spurious, consisting of a minute dense weft of 

 septate, branched, and anastomosing hyphae, bearing late- 

 rally numerous obovate, 8-spored asci ; spores continuous, 

 smooth, hyaline or tinged i)rown, elliptical; paraphyses 

 absent. 



Gymnoasciig, Baranetzky, Bot. Ztg., 1872, p. 145 ; Sacc, 

 Syll., viii., p. 823. 



Eesembling under a low power of the microscope, one of 

 the densely compacted Hyphomycetes. Baranetzky's paper, 



