FILICES. 97 



ly covered with white powder; sori numerous, very small. 

 Alaska. 



X. CRYPTOGRAMME R. Br. ROCK BRAKE. 



Sporangia on the back or near the ends of the free veins, 

 forming oblong or roundish sori, which are at length confluent, 

 and cover the back of the pinnules. Jndusium continuous, 

 formed of the membranous, somewhat altered margin of the 

 pinnule, at first reflexed along the two sides and meeting at the 

 midrib, at length opening out flat. Name from Gr. KpvxroS, 

 concealed, and ypa/uua, line, alluding to the concealed fructifi- 

 cation. A boreal genus of two species. 



i. C. acrostichoides R. Br. Stipes densely tufted, stra- 

 mineous; fronds dimorphous, sterile ones on shorter stalks, 

 tri quadripinnatifid, with toothed or incised segments; fertile 

 ones long-stalked, less compound, with narrowly elliptical or 

 oblong-linear pod-like segments. (C. crispa, forma Americana 

 Hook., Allosorus acrostichoides Spreng.) Lake Superior, Colo- 

 rado to California and northward. 



XI. PELL^EA Link. CLIFF-BRAKE. 



Sori iritramarginal, terminal on the veins, at first dot-like or 

 decurrent on the veins, at length confluent laterally, forming a 

 marginal line. Indusium commonly broad and membranous, 

 formed of the reflexed margin of the fertile segment. Name 

 from Gr. TreAAo?, dusky, alluding to the dark-colored stipes. In- 

 cludes 55 species. 



i. CHEILOPLECTON Fee, Baker. Texture herbaceous or sub- 

 coriaceous, veins clearly visible, indusium broad, in most of the 

 species rolled over the sorus till maturity. 



i. P. Breweri D. C. Eaton. Stipes densely tufted, cov- 

 ered with narrow, crisped, fulvous chaff; fronds 2' 6' long, 

 simply pinnate, the pinnae short-stalked, 6 8 pairs, membra- 

 nous, mostly 2-parted, the upper segment larger; segments ob- 

 tuse, in the fertile frond narrower; indusium continuous, pale; 

 veins repeatedly forked. Colorado to California and southward. 

 2. p. gracilis Hook. Stipes scattered, slender, 2' 3' long, 

 stramineous or pale-brown ; fronds 2' 4' long, i' 2' broad, 

 ovate, bi tripinnatifid ; pinnae lanceolate-deltoid, cut to the 

 7 



