IS 



El'IIEHACEI. 



[GONIOITEMA. 



satisfactory diagnosis, and are consequently omitted. Among these are 

 several species of Sirosiphon, e. g. 8. saxicola Naeg., 8. alpinum Kiitz., 

 8. jtulvinatus Bre"b., S. ocellatits Kiitz., which occur in Great Britain and 

 Ireland. According to Nylander, in Lamy Mt. Dor. p. 1 (note), Raco- 

 dium ebeneum (Dillw.), which from general appearance might be sup- 

 posed to belong to this tribe, has no analogy with Sirosiphon, but is 

 quite different in struc- 

 ture, containing gonidia, 

 and is probably some 

 peculiar sterile Lepraria. 



1. GONIONEMA Nyl. 

 Mem. Soc. Cherb. iii. 

 (1855) p. 163; Syn. i. 

 p. 88. Thallus byssaceo- 

 fibrillose, tubuliform, in- 

 tricate ; gonimia sub- 

 moniliformly connate in 

 one continuous series. 

 Apothecia biatorine or 

 gyalectoid ; spores 8nse, 

 simple, paraphyses slen- 

 der ; hymenial gelatine 

 (especially the thecee) 

 bluish, becoming wine- 

 red or tawny wine- 

 coloured with iodine. 

 Sperm ogones lateral, or 

 terminal, globose; ste- 

 rigmata simple, slender; 

 sperm atia oblong, very 

 minute. 



Various Scytonemas 

 probably belong to this 

 genus. If this be so, the 

 more recent name must 

 give place to that of 

 Scytonema Ag., in its 

 stricter sense. 



1. G. velutinum Nyl. 

 Mem. Soc. Cherb. iii. 

 (1855) p. 163. Thallus 

 very thin, densely pan- 

 nose, intricate, brownish 

 when moist, dark-brown 

 when dry. Apothecia 

 minute, terminal, ap- 

 pressed, somewhat concave, dark-brown, 



Fig. 1. 



Gonionema velutinum Nyl. a. Filaments with 

 two apothecia, x 30. b. Vertical sections of 

 two apothecia, x 30. c. Filaments with 

 three spermogones, x 30. d. Short frustule of 

 thallus, and d' transverse section of the same, 

 X 000. e. Apex of a filament containing a 

 meiogonimium, x 200, and e' fragment of a 

 svneoniimum composed of four gonimia, 

 /. btengmate and spermatia, x 500. 



500. 



within the 



