DICTYDLETHALIUM 241 



3. Dictydiaethalium Rost. 

 Versuch 5. 1873. 

 1875. Clathroptychium Rost., Mon. 225. 



Fructification a pseudo-aethalium, the sporangia closely compressed 

 in a single layer on an expanded base; lateral walls disappearing at 

 maturity, the sporangia then represented by the angular, usually 

 hexagonal tops, from the edges of each of which depend four to six 

 simple threads, these reaching nearly to the base and there either 

 free or united with each other; the united caps forming a continuous 

 areolate surface; spores ochraceous or clay colored. 



In 1873 Rostafinski applied the generic name here adopted, because 

 he thought he discovered close relationships with Dictydium. In 

 1875, believing his first impressions erroneous, and desirous that the 

 nomenclature might not at once mislead the student and perpetuate 

 the memory of his mistake, the same author proposed the name 

 Clathroptychium. However sensible the latter conclusion, it is plainly 

 contrary to all rules of priority. 



A single widely distributed species: 



Dictydiaethalium plumbeum {Schum) Rost. 



Versuch 5. 1873. 

 PL XV, Figs. 392, 393, 394. 



1803. Fuligo plumbea Schum., Enum. PL Saell. 2 : 193. 



1829. Reticularia plumbea (Schum.) Fr., Syst. Myc. 3 : 88. 



1831. Ostracoderma spadiceum Schw., Trans. Am. Phil. Soc. II. 4 : 262. 



1833. Licea rugulosa Wallr., Fl. Crypt. Germ. 2 : 345. 



1845. Licea applanata Berk., Hook. Lond. Jour. Bot. 4 : 67. 



1846. Lycogala lenticular e Dur. & Mont., Expl. Sci. Alg. 401. 

 1873. Reticularia lurida Berk. & Br., Jour. Linn. Soc. 14 : 82. 

 1873. Licea cinnabarina Berk. & Br., Jour. Linn. Soc. 14 : 86. 



1873. Dictydicethalium applanatum (Berk.) Rost. ex Fuckel, Symb. Myc, 



Nachtr. 69. 

 1875. Clathroptychium rugulosum (Wallr.) Rost., Mon. 225. 

 1877. Dictydicethalium dissiliens HazsL, CEsterr. Bot. Zeitschr. 27 : 85. 

 1879. Clathroptychium cinnabarinum (Berk. & Br.) Sacc, Michelia 1 : 545. 

 1892. Clathroptychium berkeleyi Massee, Mon. 53. 



Fructification thin, flat, varying from a few mm. to 10 cm. in extent 

 and 0.5-1 mm. in thickness, olivaceous, ochraceous brown, or reddish 

 brown to dark plumbeous; surface areolate, the areolae angular, usu- 

 ally hexagonal; sporangial walls lacking at maturity, but the spo- 

 rangial units evidenced by the columnar structure and the threads 

 depending from the areolae nearly to the base; base marked in areas 

 corresponding to the upper surface; true capillitium lacking; hypo- 

 thallus silvery, usually prominent and often occupying a considerable 



