Hepaticcp of North America. 27 



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

 bicular, large, often 3.8 cm. in diameter, substellately divided, 

 nearly plane, elegantly and grossly cristate-reticulate above, 

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

 often deeply channeled when dry, emarginate at the apex; fruit 

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

 0.127 0.168 mm. in diameter, subrotund, black, opaque, sub- 

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

 merous, filiform, hyaline, 1 mm. high. 



Hob. Gardens and cattle-ranges; Fla. (/. Donnell Smith). 

 Bib. Torrey Bull. VI, p. 157. 



2. SPOKGODES. Thallus with large air-cavities and with 

 <( slight depression in the upper surface immediately over the 

 fruit which is prominent on the under surface; upper surface 

 usually broken up into pits communicating with the air-cavities; 

 N/iores smaller 0.041 0.051 mm. in diameter, obtusely angular 

 or globose. Pseudo-aquatic or occurring on wet or muddy 

 ground. 



* Thalli homomorphous, terrestrial. 



16. 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 

 up into pits; fruit scattered; spores issuing through the upper 

 surface. (R. plana Tayl., E. velutina Hook, in part.) 



Hab.So. States (Di-ummond, Ravenel), 111. (Hall), Col. (Wolfe), Nev. 

 ( Watson). (Eu.) 



Bib. Syn. Hep. p. 607, Hep. Europ. p. 170. 

 Delin. Lindenberg Monog. Ric. t. XXII. 



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

 lar, 2.5 3.8 cm. 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. 



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

 common. 



Bib. Spec. Flor. Amer. Sept. p. 26, Mem. Amer. Acad. n. ser. iv, 

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



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

 Ric. t. XXVI. 



