154 LEPTOGIUM. 



Nyl. Syn. p. 107 (from North America, Drummond), is unknown 

 to me ; but the description scarcely makes clear its distinction 

 from the present, in which the thallus is often convolute, and 

 the fruit becomes regular. 



XXVIII. LEPTOGIUM, Fr., Nyl. 



Apothecia sub-scutellseform, lecanorine, or zeorine, in the 

 higher forms, but commonly biatorine in the lower. Spores 

 ovoid-ellipsoid (occurring now simple; or the spore fusi- 

 form-elongated and bi-plurilocular with entire spore-cells j 

 but, most commonly), muriform-plurilocular. Spermatia ob- 

 long ; on articulate sterigmas. Thallus foliaceous ; or rarely 

 fruticulose; membranaceous ; the cortical layer distinct; 

 the gonimia (with rare exceptions) linked together in chains. 

 The whole thallus, in the less developed species, now paren- 

 chymatous. 



* Polychidium. Thallus fruticulose. 



1. L. dendriscum, Nyl. j thallus very minute, effuse, slender, 

 dichotomously much-branched; pale-green; the intertangled 

 branches terete and smooth ; [apothecia, in a Cuban specimen, 

 small, biatorine ; the disk brownish-red, the paler margin en- 

 tire. " Spores ellipsoid, simple, decolorate, ^J mic." Nyl. 



Syn. 1, p. 135. 



Trees in inter -tropical regions. Also in Florida (Herb. 

 Michener), Tuckerman Gen. 1872. 



2. L. intricatulum, Nyl.; thallus very minute, effuse, de- 

 pressed; dichotomously branched; chestnut-brown, dull; the 

 shortish branches crowded together, unequally cylindraceous ; 

 apothecia unknown. Nyl. Syn. 1, p. 135. 



Beech trunks in the White Mountains (Oakes), Nylander I. c. 



1858. This humble but interesting because little known plant 



is comparable in some respects with the next, with which it also 

 agrees in the collogonidia occurring only in very short chains, 

 or solitary. 



3. L. muscicola (Sw.) Fr. ; thallus minute, pulvinate, irregularly 

 much-branched ; from greenish-brown passing into olive-black ; 

 the densely interwoven branches mostly terete, and more or less 



