LEPTOGITJM.] 



63 



to the anatomical structure of the thallus and the character of the apo- 

 thecia, it is divided by Nylander into four subgenera, all of which occur in 

 our Islands. 



Subgen. HOMODIUM Nyl. Flora, 1875, p. 297 (efr. Cromb. 

 Grevillea, xv. p. 12). Thallus microphylline, granulose, or variously 

 lobed or fruticulose, entirely cellular within ; gonimia rarely in part 

 moniliform. Apothecia urceolate or biatoroid; spores variously 

 septate and divided. 



Fig. 15. 



Leptoyium teimissimiim Koerb. a. Thalline lacinia\ X30. b. Transverse 

 section of thallus, x200. c. Section of apothecium (when dry), x30. 

 d. Spores, X500. 



Fig. 16. 



Leptogium muscicola Fr. a. Thalline branch, XoO. a'. Branchlet with a 

 spermogone, X30. b. Transverse and longitudinal sections of thallus, X200. 

 c. Spores, X500. d. Sterigruata and spermatia, X500. 



