282 36. ACAROSPORACEAE [ 139. Maronea 



12. Biatorella revertens (Tuck.) Herre, Proc. Wash. Acad. Sci. 12:121, 122. 1910. 

 Lecanora privigna var. revertens Tuck., Syn. N. A. Lich. 1:204, 205. 1882. 

 Thallus light greenish gray to ashy, evanescent, seen occasionally under the 



apothecia, very rarely elsewhere; apothecia small to middle-sized, 0.5-1.5 mm. 

 across, sessile, the disk concave to somewhat convex, dark reddish to black, the 

 exciple thin, of same color as the thallus, sometimes becoming flexuous and dis- 

 appearing; hypothecium hyaline; spores 8-16 X 3-6.5 /x, not numerous, and some- 

 times only 8. 



On rocks, Colorado, Nevada, and California. 



13. Biatorella albidula (Willey) Zahlbr., Cat. Lich. Univ. 5:34. 192 7. 

 Biatora albidula Willey, in Tuck., Syn. N. A. Lich. 2:130. 1888. 



Thallus very thin, smooth, white to ashy; apothecia very minute, 0.05-0.1 mm. 

 across, adnate, the disk convex, white to light brown, the exciple very thin, color 

 similar to that of the disk, soon disappearing; hypothecium hyaline; spores 6-7 X 

 2-3 it. 



On beech trees, near New Bedford, Massachusetts. 



14. Biatorella cyphalea (Tuck.) Zahlbr., Cat. Lich. Univ. 5:36. 1927. 

 Biatora cyphalea Tuck., Gen. Lich. 168. 1872. 



Thallus thin, grayish to grayish white, granular, or finally wrinkled-verrucose; 

 apothecia small, 0.5-0.8 mm. across, sessile and often clustered, the disk flat to 

 convex, pale to dark reddish and rusty brown, the exciple paler or darkening, 

 soon disappearing; hypothecium yellowish or brownish; asci ventricose; spores 

 short-ellipsoid, 3-4 X 2-3 /x. 



On elm bark, Illinois. 



15. Biatorella camptocarpa (Tuck.) Fink n. comb. 

 Biatora camptocarpa Tuck., Syn. N. A. Lich. 2:18, 19. 1888. 



Thallus thin, scurfy to granulose, greenish gray; apothecia small to middle- 

 sized, 0.4-0.9 mm. across, sessile, concave to slightly convex, the disk reddish to 

 dark livid brown, the darker, well-developed exciple rising higher than the disk 

 and finally becoming flexuous and disappearing; spores 30 or more, narrow-oblong, 

 5-11 X 2-2.5 fi. 



On trees, Florida. 



16. Biatorella hypophaea (Nyl.) Blombg. & Forss., PL Scand. 83. 1880. 

 Lecanora hypophaea Nyl., Flora 53:34. 1870. 



Thallus thin, smooth to slightly rough, granulose, greenish gray to gray; 

 apothecia small to middle-sized, 0.3-1 mm. across, sessile, round to somewhat 

 irregular, the disk flat to convex, reddish to brownish black, the exciple entire to 

 wavy, black and disappearing; hypothecium yellowish; spores oblong, apparently- 

 thickened slightly at both ends, 5-7 X 1-1.5 fi. 



On crumbling sandstone, Santa Monica Range, California. 



139. Maronea Mass., Flora 39:291. 1856. 



Thallus crustose, granulose, rudimentary, devoid of differentiation into layers, 

 attached to the substratum by hyphal rhizoids; apothecia minute to small or 

 middle-sized, partly immersed to adnate or sessile, the disk commonly flat, the 

 exciple thin to thick, colored like the thallus, irregular, rarely disappearing; hypo- 

 thecium hyaline; hymenium hyaline and becoming indistinct; paraphyses un- 

 branched or more or less forked at the apices; asci clavate to cylindrico-clavate; 



