Hepaficd' of Xoytli America. 27 



15. R. Donnellii Aust. Dioecious; primary thallus or- 

 l)icular, large, often 8.8 cm. in diameter, substellately divided, 

 nearly plane, elegantly and grossly cristate-reticulate above, 

 pale green both sides; divisions more or less di-tricliotomous, 

 often deeply channeled v^^hen dry, emarginate at the apex; fruit 

 in a single row, immersed in the midrib; spores very large 

 0.127 — 0.108 mm. in diameter, subrotund, black, opaque, sub- 

 tuberculate; male thallus usually a little larger; ostioles nu- 

 merous, filiform, hyaline, 1 mm. high. 



Hah. — Gardens and cattle-ranges; Fla. (J. Donnell Smith). 



Bib.— Torrey Bull. VI, p. 157. 



§ 2. Spongodes. Thallus tritJi lanje a/r-cavifies and irif/i 

 a sliglit depression in the upper sitrface inuiiediafelij orer the 

 fruit u-hich is prominent on the under surf are; upper surf are 

 usuaUy broken up into pits vomnmnirating iritJi the air-cavities; 

 sj>ores smaller 0.041—0.051 mm. in diameter, obtusely angular 

 or f/lobose. Pseudo-aquatic or occurring on wet or muddy 



ground. 



* Thalli ]iomomo)-j>hous, terrestrial. 



l(S. R. crystallina L. Thallus orbicular, 1 — 2 cm. in 

 diameter; divisions obcordate or cuneate, bifid or bilobed, plane 

 above, the margins subcrenate, the upper surface much broken 

 u]) into pits; fruit scattered; spores issuing through the upper 

 surface. {B. plana Tayl., B. relutina Hook, in part.) 



Hah.—^o. States (Dmmmond, Ravenel), 111. {Hall), Col. [Wolfe), Nev. 

 {Watson). (Eu.) 



Bifc.— Syn. Hep. p. 607, Hep. Europ. p. 170. 

 Delhi. — Liudenberg Monog. Ric. t. XXII. 



17. R. lutescens Schwein. Thallus light green, orbicu- 

 lar, 2.5 — 3.8 cjn. in diameter; divisions 6 — 8, linear, twice or 

 three times forking, narrowly channeled above, obcordate and 

 convex-thickened at the apex, with delicate, whitish, obliquely 

 ovate, appressed scales, and destitute of rootlets above the mid- 

 dle underneath; reproductive organs entirely unknown. 



Hah.— In exsiccated pools and ditches ; Can. to Fla., Mo. and Tex.; 

 common. 



jB*.— Spec. Flor. Amer. Sept. p. 26, Mem. Amer. Acad. n. ser. iv, 

 p. 176, Pro. Phil. Acad. 1869, p. 234. 



DeZin.— Mem. Amer. Acad. n. ser. iv, t. IV; Lindenberg Monog. 

 Ric. t. XXVI. 



