LEPTOGIUM. | COLLEMEI. 63 
to the anatomical structure of the thallus and the character of the apo- 
thecia, itis divided by Nylander into four subgenera, all of which occur in 
our Islands. 
Subgen. HOMODIUM Nyl. Flora, 1875, p. 297 (cfr. 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. 
Leptogium tenuissimum Koerb.—a. Thalline lacinie, x30. 0. Transverse 
section of thallus, x200. ¢. Section of apothecium (when dry), X30. 
d. Spores, x 500. 
Fig. 16. 
Leptogium muscicola Fr.—a. Thalline branch, x80. a’. Branchlet with a 
panei x30. 0. Transverse and longitudinal sections of thallus, x 200. 
c. Spores, x500. d. Sterigmata and spermatia, x 500, 
