ONOCLEA. CLXIV. FILICES. 633 



Frond twice as long as wide, of a grayish hue, the two lower divisions con- 

 sisting of 1 3 pairs of leaflets with a large, terminal segment. All the seg- 

 ments lance-linear, distinct, with margins conspicuously revolute. Stipe and 

 rachis dark purple, with dense, paleaceous haira at base. June Aug. 



3. P. GRACILIS. Michx. (Cheilanthes. Spreng.) 



Frond slender, lanceolate, sterile ones pinnate, leaflets pinnatifid, segments 

 broad-ovate, obtuse ; fertile bipinnate, leaflets linear-oblong, crenate ; stipe dark 

 brown. A delicate species, growing on rocks. Fern 46' high, smooth and 

 shining in all its parts. Aug. 



8. CHEILANTHES. Swartz. 

 Gr. %Xof, lip, avSos ; from the form of its indusia. 



Sori roundish, distinct, situated at the margin of the fronds ; in- 

 dusium of membranous, distinct, inflexed scales, opening inwardly, 

 sometimes continuous with the frond. 



C. VESTITA. Swartz. (Nephrodium lanosum. MX.) Hairy Cheilanthes. 

 Stipe and rachis hairy ; frmid bipinnate, oblong-ovate in outline, hairy on 



both sides ; lea/lets alternate ; segments oblong, alternate, sessile, distinct, crenately 

 pinnatifid, the ultimate segment very entire ; sori finally continuous along the 

 margin. Rocky banks, Mid. and W. States, frequent. Stipe slender, rigid, 

 2 3' long, dark brown. Fronds 3 6' by 1 2'. Leaflets lance-ovate in out- 

 line, 6 12" long. Sori marginal, distinct when young, finally crowded. July. 



9. ADIANTUM. 



Gr. a. privation, <5tatvco. to moisten; as the rain slides off without wetting it. 



Sori oblong or roundish, marginal ; indusia membranaceous, aris- 

 ing from the reflexed margins of distinct portions of the frond and 

 opening inwardly. 



A. PEDATUM. Maidenhair. 



Frond pedate ; divisions pinnate ; segments oblong-rhomboid, incisely 

 lobed on the upper side, obtuse at apex ; sori oblong, subulate. This is, doubt- 

 less, the most beautiful of all our ferns, abounding in damp, rocky woods. 

 Stipe 814' high, slender, of a deep, glossy purple approaching to a jet-black. 

 At top it divides equally into 2 compound branches, each of which gives off, 

 at regular intervals, 6 8 simply pinnate leaflets from the outer side, giving the 

 whole frond the form of the crescent. Ultimate segments dimidiate, the lower 

 margin being bounded by the mid vein and the veinlets all unilateral. July. 



10. DICKSONIA. L'Her. 



In honor of James Dickson, a distinguished English cryptogamist. 



Sori marginal, roundish, distinct ; indusium double, one superficial, 

 opening outwards, the other marginal and opening inwards. 



D. PILOSIUSCULA. Willd. Fine-haired Mountain Fern. 



Frond bipinnate ; leaflets lanceolate, sessile ; segments pinnatifid, decurrent, 

 oblong-ovate, ultimate segments toothed ; stipe a little hairy. A large and deli- 

 cate fern, in pastures, roadsides, among rocks and stones. Fronds 2 3f high, 

 in tufts, and remarkable for their numerous divisions and subdivisions. Stipe 

 and rachis smooth, with the exception of a few, soft, scattered hairs. Leaflets 

 alternate, approximate ; segments deeply divided into 4- toothed, ultimate seg- 

 ments. Sori minute, solitary, on the upper margin of the segments. July. 



11. ONOCLEA. 



Gr. ovos, a kind of vessel, K\EIW, to close ; alluding to the contracted thecae. 



Thecas covering the whole lower surface of the frond ; indusia 

 formed of the segments of the frond, whose margins are revolute and 

 contracted into the form of a berry, opening, but not expanding. 



O. SENKIBILIS. Sensitive fern. 



Sterile frcnds pinnate ; k'ajlfts lanceolate, acute, laciniate, the upper ones 



