188 



nula3 numerous, contiguous, oblong-lanceolate, acuminate, the point 

 sharply serrate, slightly stipitate ; tertiary segments ovate-oblong, 

 cuneate at the sessile base, bluntish, 4-8 li. 1., 2-3 li. w., serrated ; 

 costae interruptedly winged in the outer part, costulae so throughout ; 

 veins simple or forked ; synangia one to each vein, a short way within 

 the margin, the valves at length spreading. — M. Icevis, J. Sm. 

 Dicostegia, Presl. 



Very abundant, gregarious in forests at 5,000-6,000 ft. alt., often 

 covering extensive areas. "When the petiole drops away, it leaves a 

 a short joint at the base with the gills adhering to it. This is vivipa- 

 rous in the axils of the large auricles or gills, two buds appearing above 

 and two below on the rounded back. One only however is usually de- 

 veloped, and this from either of the basal axils. The joints lie about 

 plentifully, and when the plantlets are strong enough they root into 

 the ground and proceed to maturity. Reproduction seems to be carried 

 on much more largely in this way than from spores. The whole frame- 

 work of the fronds is h =ihy, and in drying becomes shrivelled and flat. 



G^NUS 11. Dan^a, Smith. 



Synangia linear or oblong, more or less immersed, running from the 

 midrib to the margins od the free veins, very close and covering, ex- 

 cept the costse, the whole nder surface, sessile, and broadly attached 

 by the base, each one composed of a double row of numerous sporangia 

 fused and blocked together, opening eventually by small apical pores ; 

 fronds simple or pinnate, dimorphous, the fertile somewhat reduced ; 

 stipites with or without distant nodes, and articulated at the auricled 

 base. 



This is entirely an equatorial American genus, and the largest of the 

 sub-order. There is no great diversity of form in the genus, and the 

 members differ chiefly in size and substance, number of pinnae, number 

 of nodes to the stems, and direction of growth of the rootstock. The 

 sporangia are biserial, fused together into concrete linear synangia, 

 which are immersed in a gum, or, when dry, gray-parchment-like sub- 

 stance, which surrounds them like a mould and forms thin partitions 

 between their sides. The sporangia are multitudinous. Moderate sized 

 fronds of M. nodosa contain from 300,000-400,000 each. 

 Fronds pinnate. 



Stipites with 1-4 nodes. 

 Pinnae under 1 in. broad. 



1. D. alata. 



2. D. stenophylla* 

 Pinnae over 1 in. broad. ^ 



3. D. elliptica. 



Stipites devoid of nodes. 



4. D. nodosa. 



1. D. alata. Smith. — Stipites fleshy caespitose, erect, 6-9 in. 1,, 

 scaly throughout ; nodes 1-2 ; fronds oblong pinnate, usually rather 

 narrower at the bottom and top, no terminal segment ; beneath scaly, 

 chiefly on the ribs, both sides rather pale green ; rachis fleshy, scaly, 

 narrowly winged interruptedly, with a small bud at the apex ; pinnae 

 8-12 or 14 to a side spreading, shortly stipitate, rounded at the base, or 

 the lower ones sometimes more cuneate, the apex acute, or cuspidate 



