CATALOGUE. 323 



vated in conservatories in the Atlantic States bave fronds generally less compound than those gathered 

 on their native hillsides, and it is in these cultivated plants only that I find sterile fronds with the pin- 

 nules flattened out. Otherwise the pinnules are closely revolute, and when trifoliolate, as they almost 

 always are in a state of nature, they strongly suggest the claws of a bird's foot, whence the specific name 

 chosen by Hooker, a name which I bave no wish to disturb through a technical claim of priority. Platylvma 

 brachypterum of Moore answers well to a form collected in the Sierras by Bolander, by Mrs. Austin, and 

 by Mrs. Pulsifer Ames, a form with minute pinnules when growing on exposed rocks, but with elongated 

 ones iu a plant wet with spray escapiug from a neighboring flume. Moore's P. helium seems to be the 

 same as the smaller form of var. brachyptera, except that some of the measurements given in The Gard- 

 eners' Chronicle, and copied" by Baker in the second edition of Synopsis Filicum (p. 477), are incompre- 

 hensible, and probably incorrectly printed. P. helium of Eastern conservatories is not Moore's plant, and 

 is ordinary P. Ornitlwjnts slightly modified by cultivation in a moister atmosphere. 



Pellaea densa, Hooker. 



Rootstocks rather slender, entangled, chaffy with nearly black narrow- 

 scales; stalks densely tufted, wiry, and very slender, dark chestnut-brown, 

 dull or polished, 3-9 inches long ; fronds ovate or triangular-oblong in out- 

 line, I i-2£ inches long, densely tripinnate ; segments 3-6 lines long, linear, 

 nearly sessile, sharp-pointed or mucronate, in the fertile fronds entire, and 

 having the margin narrowly recurved, and provided with a distinctly paler 

 involucre, in the very rare sterile fronds broader and sharply serrated, 

 especially towards the apices.— Sp. Fil. ii, p. 150, t. cxxv, B. Onychium 

 densum, Brackenridge, Ferns of U. S. Exploring Exped. p. 120, t. 13, f. 2. 



Sierras of California from the Yosemite to the Castle Mountains, Brewer, Bolander, etc. Oregon 

 Rogue River (Brackenridge), and near Port Orford, Gen. A. T. Eautz. Near Jackson's Lake, Wyoming 

 Territory, Hayden's Expedition. A very distinct species, not in the least related to those just described. 

 Brackenridge, who considered it an Onychium, noticed that the plant bears a close resemblance in habit 

 to Cryptogramme acrostichoides, and Hooker remarks the same similarity. A thin cross-section of a seg- 

 ment shows the involucre to be a very delicate special organ, growing just within the proper margin of 

 the segment. 



$3. PLATYLOMA. J. Smith, Baker. 



"Texture coriaceous, the veins usually hidden, the ultimate segments broad 

 and flat, the involucre so :iarrow that it is soon hidden by the fruit" 



PeBIar-a Sridgesii, Hooker. 



Stalks 3-6 inches long, wiry, dark-brown, smooth and polished, many 

 rising from a short, creeping rootstock, which is chaffy with very narrow 

 scales; fronds as long as the stalks, simply pinnate; pinna; 5-18 pairs, 

 mainly opposite, nearly sessile, glaucous-green, coriaceous, sterile ones 

 orbicular or obscurely cordate, 4 5 lines long, rarely larger, fertile ones a 

 little narrower, commonly at first conduplicate, and so seemingly lunate; 

 involucre narrow, formed of the whitish cartilaginous margin of the pinnse, 



