340 FILICES. J'dlwa. 



nate ; pinnre several pairs, so.^silc, ascendin,!,' or apprcssed to the rhacliis, very sliort, 

 often broader than lonj,' ; piunules 5 to 13 to a pinna, 3 to G lines long, crowded, 

 oblong-linear, greenish-glaucescent, nincronulate, the edges much rolled back, making 

 the pinnules nearly terete, and covering the sori. — Syn. Fil. 2 ed. 477; Eaton, 

 Ferns of N. Anier. ii. 9, t. 47, fig. 4-6. Plati/loma hrachijptermn, T. Moore, in 

 Oard, Chronicle, 1873, 141. Pclla'a Oniithopiis, var. brac/ti/j>(tra, Eaton, in Torr. 

 Jiot. bulletin, iv. IG, and Eerns of the .Southwest, 322. 



Kocky places in the Sierra Nevada {Bolnndcr, Jfra. Ames, Mrs. Avstin, KcUofjr/ k Ifurfurd) ; 

 Lassen's I'euk (Lcmmoii) ; Wi-averville, Klcclicrfjn: In moist situations tlie growtli is niiieli larger 

 than in dry places. Plalyloiaii helium, Moore, is pioliably a form of this sjieeies, but is not 

 known to me. The common plant so named is P. Ornilhoims, modified by cultivation, 



-1- -f- Fronds ti'ipbinafe wlien fullij developed. 



.5. P. Ornithopus, Hooker. Kootstock short, thick, knotted, densely chaffy 

 with very narrow dark-brown .scales : stalks clustered, rather stout and very rigid, 

 dark-i)urplish or almost black, polished, 2 to 10 inches long : fronds 4 to 12 inches 

 long, rigid, broadly ovate-lancecjlate, tripinnate or in smaller plants bipinnate ; pri- 

 mary pinnai spreading or obliquely ascending, liuear, bearing from a few u[) to IG 

 pairs of usually trifoliolate, but varying to simple or to o - 7-foliolate, nearly sessile 

 pinnules, which are commonly 1 \ to 3 lines long, coriaceous, mucromilate, glauces- 

 cent beneath, roundish-rpuulrate in the very rare sterile fromls, and in the fertile 

 fronds having the margins rolled back to the niiilvein. — 8p. Eil. ii. 143, t. IIG, A ; 

 Eaton, Eerns of the Southwest, 322, and I'Y'rns of N. Amer. ii. 11, t. 47, lig. 7- 10. 

 Allosovus aHdroiiiidi('j'i)li.(i», Honker, I'l. llartweg. 312, not of Kaull'uss. A. mticro- 

 vatus, Eaton, in Am. Jt)urn. Sci. 2 ser. xxii. 138. J', ■mucronata, Eaton, Hot. Me.x. 

 Bound. 233, in part. 



Dry exposed rocks, very common fiom Mendocino f'ounty to San l^iego; also on (luadalnpc 

 Island, Piibncr. Tlie trii'oliolate pinnules bear consideralile resemblance to the three claws of a 

 bird's foot, whence the specific name. Small forms with bi|iinnate fronds have pas.sed for P. 

 Wrujhlima, but do not hirm the massive rootstocks of the l.ili.r, and are .sud by Mr. AV right to 

 cease their yearly growth long before it. 



6. P. densa, Hooker. Hootstocks r.ither slender, branching and entangled, 

 chatfy with narrow blackish scales: stalks densely tufted, slender, wiry, dark-brown, 

 dull or polished, 3 to 9 inches long: fronds ovate or dtdtoid-ovate, U to 2i inches 

 long, closely tripinnate; segments 3 to G lines long, nearly sessile, lance-linear, acuto 

 or inucronate, in the rare sterile fronds sharply serrated, in the fertile fronds entire, 

 the margins narrowly recurved and ])earing a i)aler distinct invohicre. — Sp. Eil. ii. 

 150, t. 12r), 1> ; Eaton, Eerns of X. Amer. i. 77, t. 11, lig. 1. Oni/cliitnn densum, 

 Brackenridge, Eil. of U. 8. Expl. Exped. 120, t. 13, fig. 2; Torrey, Pacif. Ii. liep. 

 iv. IGO. 



Clefts of rocks, not rare at elevations of 6,000 to 8,000 feet in the Sierra Nevada, from the Cas- 

 tle Moinitains to the Yosemite; also in Oregon and in Wyoming Territory. The indusium is a 

 very delicate special organ, growing just within the margin of the segments. 



§3. Texture coriaceous, nsualli/ conceali/if/ the veins; nltlniafe segments broad 

 and flat, tlie Involucre iiarroio and at length hidden by the confluent .sj/o- 

 ranyla.- — Pr.ATVLOMA, Hooker & Baker. [Platyloma, J. Smith.) 



7. P. Bridgesii, Hooker. Kootstock short, creeping, densely chatfy Avith nar- 

 row castaneous scales : stalks 3 to G inches long, clustered, terete, wiry, dark red- 

 dish-brown, smooth and shining : fronds as long as the stalks, linear-oblong, sirajjly 

 pinnate ; piniue 5 to 18 pairs, mostly opposite!, subsessile, glaucous green, coriaceous; 

 sterile ones orbicular or subcordate, 4 to 5 lines long, rarely larger ; fertile ones 

 .somewhat narrow, often at lirst conduplicato and apparently lunate : involucre nar- 

 row, formed of the whitish cartilaginous margin of the i)inn;c, soon llattened out and 

 exposing the .sori conlluent in a broad intramarginal band. — 8p. Eil. ii. 238, and 

 iii, t. 142, B; E;iton, Eerns of N. Amer. i. 327, t. 4-3, fig. 1-4. 



