RICCIACE^E. 731 



* Thallus with white scales beneath (dark purple in n. 4), the margin naked. 



2. R. sorocarpa, Bisch. Thallus 3 - 8" in diameter, pale green becom- 

 ing whitish, finely reticulate, subradiately or dichotomously divided, the ob- 

 long-linear segments subacute, deeply sulcate, with a few inconspicuous scales 

 toward the apex not extending beyond the margin ; margins erect when dry ; 

 spores issuing through chinks early appearing along the groove above. 

 Thin rocky soil and cultivated fields, Closter, N. J. (Austin), western N. Y. 

 (Clinton), and 111. (Hall). (Eu.) 



3. R. lamellosa, Raddi. Thallus pale green, elegantly reticulated, sub- 

 radiately divided, the divisions obovate or obcordate, bifid or 2-lobed, 2-5" 

 long, channelled at the apex, with membranous ascending margins, and fur- 

 nished beneath with transverse scales which extend considerably beyond the 

 margin; spores much as in n. 2. Thin rocky soil, Closter, N. J. (Austin). 



4. R. nigrella, DC. Thallus dichotomously divided, the divisions linear, 

 channelled, with entire narrowly membranous margins, green above, dark 

 purple beneath and furnished with transverse semicircular scales not ex- 

 ceeding the margin.^ Rocky ground, N. Y. (Torrey), and Chester, Penn. 

 (Porter). (Eu.) 



# * * Thallus more or less ciliate, naked beneath or obsoletefy squamous along 



the extreme edge. 



5. R. arvensis, Aust. Thallus much divided, 3-9" broad, papillose- 

 reticulate, dull green both sides, becoming fuscous above, the flat margins at 

 length purple ; divisions sulcate, dichotomous, the linear-elliptic or subspatu- 

 late lobes acutish and obsoletely emarginate ; cilia whitish, very short and 

 inconspicuous or nearly wanting ; capsules aggregated toward the apex ; 

 spores 71-84/i broad, dark fuscous, reticulate, with pellucid margin. Var. 

 nfuTA, Aust., decidedly ciliate and with spine-like hairs scattered over the 

 upper surface ; divisions broader, more obtuse ; spores nearly black, larger 

 (84-lOlju) and smoother. Cultivated fields and (the var.) rocky places, 

 Closter, N. J. (Austin). 



6. R. Lescuriana, Aust. Stellately or subcruciately divided, the obcor- 

 date or cuneate-liuear divisions 2-6" long, punctate-reticulate, subglaucous 

 or ashy-green both sides or becoming purple beneath, the slightly concave 

 lobes emarginate, closely ciliate with short obtuse spine-like white hairs ; 

 capsules scattered, chiefly near the base of the divisions ; spores 7 1 - 83 fj. broad, 

 dark brown, reticulate, not margined. Cultivated fields and rocky grounds, 

 N. J. to 111., and southward. 



2. SPONGODES. Thallus with large air-cavities usually opening by pits 

 through the upper surface, and with slight depressions over the capsules 

 which are prominent beneath; spores 41-51yu broad, obtusely angular or 

 globose, ; terrestrial. 



7. R. crystallina, L. Orbicular, 6-9" broad, the obcordate or cuneate 

 divisions bifid or 2-lobed, flat above and the surface much broken up into pits, 

 the margins subcreuate ; capsules scattered ; spores issuing through the upper 

 surface. On mud flats, 111. (Hall), west and southward. (Eu.) 



8. R. lutescens, Schweiu. Orbicular, 1 - H' in diameter, light green ; 

 divisions 6-8, linear, 2-3 times forked, narrowly channelled, obcordate and 



