458 FILICES. 



riculate at base on the upper side, subsessile; the uppei ones smaller and 

 only fertile ; sori at length confluent. Ncphrodiuvi acrostichoides Mich. 



var. incisum Gray : segments unequally and incisely toothed ; sori mostly 

 distinct. A. Schiceinitzii Beck 13ot. \st Ed. 



Rocky and low shady places. Can. to Car. W. to Miss. June — Aug. %. 

 — An erect fern 12 — 18 inches high, growing in clusters. -Si/jje short, pale, and 

 with the rachis very chaffy. Frond lanceolate, very acute or cuspidate, pale 

 green. Sori rather large, in a single or double row, at length confluent and 

 covering the whole lower surface of the terminal leafets. Indusium orbicular, 

 .Var. incisum, has been found in Oneida county, N. Y., by Gray, and near Phil- 

 adelphia by Schweinitz. Terminal Shield-fern. 



** Frond pinnatc-pinnatifid. afl 



2. A. Thelypleris Swartz : frond pinnate; pinnae mostly opposite, linear- 

 lanceolate, sessile, deeply pinnatifid, the lower ones longer ; segments ovate- 

 oblong, rather ac<!le, the margin shghtly crenulate. revolute when in fruit; 

 sori small, a short distance from the margin, contiguous, at length conflu- 

 ent. Poll/podium Thelypteris Linn. 



Wet woods and swamps. Can. to Del. July. %. — Slipe about a foot long, 

 smooth and naked. Frond 6 — 12 inches long, oblong-lanceolate in outline, 

 deep green and delicate. Sori between the margin and midrib of the segments, 

 at length confluent and usually covering their w'hole under surface. Indusium 

 orbicular-reniform. Marsh Shield-fern. 



3. A. Noveboracense Willd. : frond pinnate ; pinnae linear-lanceolate, 

 sessile, deeply pinnatifid, the lower ones gradually smaller ; segments ob- 

 long, obtuse, entire, ciliate; sori minute, nearly marginal, distinct. A. 

 thelypteroides Swartz. Ncphrodiuvi thelypleroidcs Mich. 



Moist woods. Can. to Car. July. %. — A fern about as large as the pre- 

 ceding, but of a more rigid habit. Stipe smooth or slightly^fvubescent. Frond 

 pale green ; the segments linear-oblong and sometimes a little acute. Sori in 

 two rows. Indusium orbicular-reniform. Perhaps not distinct from A. The- 

 lypleris. New York Shield-fern. 



4. A. C9-istaium Sioartz: stipe nearly naked; frond pinnate, (nearly hi-" 

 pinnate,) lanceolate, somewhat rigid ; pinnae somewhat cordate, oblong, 

 deeply pinnatifid ; segments oblong, obtuse, doubly serrate : sori near the 

 midrib. A. Lancastriense Spreng. 



Moist woods. Can. to Del. ; rare. July. %. — Stipe stout, somewhat chaffy, 

 varying from tawny to brown. Frond U — 2 feet long, linear-lanceolate in its 

 outline, bright green ;. lower pinnas broad at the base. Sori middle-sized, dis- 

 tinct, dark brown, mostly in two rows, usually on the upper half of the frond. 



Crested Shield-fern. 



5. A. Goldianum Hook. : frond pinnate, broad-ovate ; pinnae deeply pin- 

 natifid, lanceolate, acuminate ; segments oblong,^ubacute, somewhat fal- 

 cate, mucronate-serrate ; sori in two rows near the midrib on the lower 

 segments. A. Filix mas Pursh not of Willd. 



Moist woods. Can. to Del. July. %. — Fernlh — 3 feet high, with the siipe 

 somewhat chaffy. Fronds — 12 inches wide, yellowish-green. Resembles A. 

 cristatum more than any other species, but can at once be distinguished by the 

 broader frond, by the form of the pinflsB, which are never broader at base, and 

 by the narrower and slightly falcate segment". Goldie's Shield-fern. 



*** F?-ond bipinnate. 



6. A. marginale Swartz .• stipe chaffy ; frond bipinnate ; pinnaj lance- 



