14 
SYNOPSIS OF THE GENERA. 
23. PoLYBOTRYA, Humholdt. — Fronds (fertile) contracted. Veins pinnate, simple ; venules free, 
external, Sori occupying one or both sides of the spiciform segments of the contracted fronds. 
Section II. Symphoplilebiece, J. Smith. — Veins anastomosing or reticulated. 
24. Olfersia, Raddi. — Fronds (fertile) contracted and soriferous on both surfaces. Veins forked, 
parallel, internal, their apices combined with a transverse continuous marginal vein. Sori dense, 
occupying the whole surface of the fertile fronds. 
25. Anetium, Splitgerher . — Veins uniform, reticulated, the areoles elongate trapezoid or hexagonal. 
Spore-cases sparingly scattered over the under surface, often collected into small groups or lines. 
26. Hvmenodium, Fee. — Fro?ids (fertile) contracted. Veins uniform, internal, reticulated, forming 
large elongated trapezoid hexagonal areoles. Sori densely covering the under sui’face of the fertile 
fronds. Rhizome decumbent, criniferous. 
27. Acrostichum, Linnceus. — i'V-onJs contracted in the fertile pinnee. Fefws uniform reticulated, 
forming small elongated usually tetragonal and parallel areoles. Sori densely covering the under sur- 
face of the fertile pinnte. Rhizome erect, caudiciform. 
28. Platvcerium, Resvaux. — Fronds dissimilar,, stellately pubescent, the fertile forked. Veins 
repeatedly forked and distantly anastomosing ; venules internal, compoundly reticulated, with vari- 
ously du-ected free veinlets terminating in the areoles. Sori forming irregular patches near the ex- 
tremities of the fronds or on special lateral thickened lobes; receptacle consisting of an accessory layer 
of parallel anastomosing veinlets crossing the sterile ones, and producing crowded linear lines of 
spore-cases. 
29. CvRTOGONiUM, J. Smith. — Fronds (fertile) contracted. Veins pinnately costseform ; venules 
arcuately or angularly anastomosing, producing from their exterior sides or points of confluence one 
or more excurrent free or iiTegularly anastomosing veinlets. Sori occupying the under surface of the 
fertile fronds, or crowded on the venules. 
30. Gymnopteris, Bernhardi. — Fronds (fertile) contracted. Vems uniform or costaeform ; venules 
compoundly anastomosing, producing variously directed, straight or curved, free veinlets, terminating 
within the areoles. Sori univei’sal on the under surface of the fertile fronds. 
Trihe III. PTERIDEiE, .7. Smith, — Sori round or elongated, transverse, marginal, intramarginal, 
or costal, furnished with a special lateral indusium, free at the inner edge, and attached at the 
exterior side of the sporangiferous receptacle, which is parallel with the midrib or margin. 
Section I. Chilosorcce, J. SmitR. — Sori marginal. 
31. Adiantum, Linnceus . — Costa excentric or wanting; veins unilateral or -radiating, forked; 
venules direct, their apices terminating in the axis of the indusium. Sori round, reniform, oblong or 
linear, continuous or interrupted ; indusium venose, sporangiferous on its under surface. 
32. Cheilanthes, Swartz . — Vems forked ; venules direct, their apices free and sporangiferous. 
Sori round, solitary or contiguous, often becoming confluent ; indusium usually reniform, rarely 
oblong, and including niore than one sorus. 
33. Hvpoeepis, Bernhardi. — Veins forked or pinnate, the lower exterior venule soriferous. Sori 
round, marginal opposite the sinus of the segments, partly concealed by a spurious indusium formed 
of a reflexed marginal crenule. 
34. Platyloma, j. Smith . — Veins forked ; venules direct, free, and sporangiferous at the apex. 
Sori oblong, laterally confluent into a broad marginal band ; indusium narrow, attached to the outer 
side of the broad sporangiferous receptacle. 
35. Doryopteris, J. Smith. — Veins nearly uniform, internal, reticulated, forming elongated 
oblique areoles. Sori linear, continuous ; indusium narrow. 
36. Litobrochia, Presl . — Vems external, elevated, arcuately and angularly anastomosing, forming 
