458 FILICES. 



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

 only fertile ; son at length confluent. Ncpkrodium acrostichoid.es Mich. 



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

 distinct. A. Schweinitzii Beck Dot. 1st Ed. 



Rocky and low shady places. Can. to Car. W. to Miss. June Aug. *2J.. 

 An erect fern 12 18 inches high, growing in clusters. Stipe 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 pinnate-pinnatijid. 



2. A. Thelypleris Swarlz : frond pinnate ; pinnse mostly opposite, linear- 

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

 oblong, rather acute, the margin slightly crenulate, revolute when in fruit; 

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

 ent. Poli/podiam Theh/pteris Linn. 



Wet woods and swamps, ("an. to Del. July. 1\.. Stipe 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 arid usually covering their whole 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. 

 tJielypteroides Swa.rtz. Nepkrodium thelypteroides Mich. 



Moist woods. Can. to Car. July. r t\.. A fern about as large as the pre- 

 ceding, but of a more rigid habit. Stipe smooth or slightly pubescent. 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. cristatum Swariz: stipe nearly naked; frond pinnate, (nearly bi- 

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

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

 midrib. A. Lancastricnse Spreng. 



Moist woods. Can. to Del. ; rare. July. 1\.. Stipe stout, somewhat chaffy, 

 varying from tawny to brown. Frond 1J 2 feet long, linear-lanceolate in its 

 outline, bright green; lower pinnse 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 ; pinnse deeply pin- 

 natifid, lanceolate, acuminate ; segments oblong, subacute, somewhat fal- 

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

 segments. A. Filix mas Pursh not of Wittd. 



Moist woods. Can. to Del. July. '4- Fern 1* 3 feet high, with the stipe 

 somewhat chaffy. Frond 6 12 inches wide, yellowish-green. Resembles A. 

 cristatum more than any other s-pecies, but can at once be distinguished by the 

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

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



*** Frond bipinnate. 



6. A. marginal* Swarlz stipe chaffy ; frond bipinnate ; pinnae lance- 



