Ceratopteris.] filices. 443 



5. CERATOPTERIS, Brongn. 



Spore-cases globular, opening in 2 valves with an incomplete or rudimen- 

 tary ring, arranged along the longitudinal veins of the narrow segments of 

 the fertile fronds, and loosely covering their under surface. Indusium con- 

 tinuous and membranous, formed of the revolute margins of the segments. 

 Spores marked with 3 series of concentric rings. — An aquatic annual, the 

 barren and fertile fronds distinct. 



A genus limited to a single species. 



1. C. thalictroides, Brongn.; Hook. Spec. Fil. ii. 235; Gen. Fil. 

 t. 12. Fronds bipinnate, the fertile ones erect, 6 in. to 1 ft. high, with linear 

 acute segments f to 1 in. long ; the margins revolute and covering the fruc- 

 tification their whole length. Barren fronds shorter and more spreading, 

 the segments cuneate, with 2 or 3 oblong or lanceolate lobes, of a soft half- 

 succulent texture. Veins reticulate. — Parkeria pteridioides, Hook. Exot. Fl. 

 t. 147 and 231 ; Hook, and Grev. Ic. Fil. t. 97. 



Hongkong, Seemann ; in the Happy Valley, at the water's edge, Wilford. Widely distri- 

 buted over tropical Asia, Africa, America, and Australia. 



SERIES II. TRUE FERNS. 



Spore-cases erect, helmet-shaped, with a vertical ring opening by a transverse fissure, usually 

 stipitate, very small and crowded in the sort. 



6. ACROSTICHUM, Linn. 



Spore-cases not distributed in distinct sori, but densely crowded and cover- 

 ing the whole under surface of the fertile segments, which are either on the 

 same or on distinct fronds from the barren ones, and usually narrower. In- 

 dusium none. — Herbaceous Ferns. Fronds in the Hongkong species all 

 simply pinnate, simple or variously divided in others. 



A large genus, chiefly tropical, common to the New and the Old World. 



Barren segments coriaceous, the veins all equally reticulate, the fertile on 



the same frond 1. A. aureum. 



Barren fronds membranous, the primary veins pinnate, fertile fronds distinct. 

 Segments 3 to 5 (rarely 1), broadly oblong, 6 to 10 in. long, decurrent 



at the base 2. A . decurrens. 



Segments numerous, lanceolate, usually petiolulate, 3 to 5 in. long . 3. A. repandum. 



1. A. aureum, Linn. ; Moore, Ind. Fil. 5. Fronds firm, 1 to 3 or 4 ft. 

 high, pinnate. Barren segments linear-oblong, about 4 to 8 in. long, very 

 obtuse, oblique at the base and petiolulate, the midrib prominent, the very 

 numerous equally reticulate veinlets covering the under surface. Fertile seg- 

 ments usually occupying the upper part of the frond and rather smaller than 

 the barren ones, the fructification of a rich golden colour when fresh. 



Hongkong, Wright ; at Tytamtook, JJrquhart. Common in most tropical and subtro- 

 pical countries. 



2. A. (Gymnopteris) decurrens, Hook. Fil. Exot. t. 94. Fronds 1-J- 

 to 2 ft. high, pinnate or the outer barren ones rarely simple ; the stipes rich 

 brown, with subulate scales at the base. Segments of the barren fronds 

 usually 3 or 5, oblong, acuminate, the lateral ones 5 to 9 in. long, the terminal 



