INTRODUCTION. 47 
order being referred—one to Osmundinee, three to Trichomaninee, 
and the remainder to the Polypodinee. 
The group Polypodinee is divided into twenty-three sections, of 
which the following only are represented in the British Flora :一 
Lomariee or Blechnee, having linear indusiate intramarginal sori transverse to 
the veins. 
Adiamtee, having oblong sori, borne on the under side of the indusium itself, and 
therefore resupinate. i 
Pteridece, having linear indusiate marginal sori, transverse to the veins. 
Aspleniew, having oblong or linear indusiate sori, lying obliquely, parallel with the 
veins. 
Gymnogrammec, having oblong or linear oblique naked sori. 
Polypodiece, having punctiform naked dorsal sori. 
Aspidiew, having punctiform indusiate dorsal sori. 
Oystopteridee, having punctiform covered dorsal sori, the indusium being semi- 
involucriform. 
Peranemece or Woodsiee, having punctiform involucrate dorsal sori. 
These sectional groups, are arranged in the foregoing order, in 
our Index Filicum, the intention being to give precedence to those 
in which the fertile principle is most evident, these being considered 
as having their organs most perfectly developed. 
The principal modern arrangements of Ferns which the student 
will derive advantage from consulting, are those of Professor Fée,* 
Mr. John Smith,t and the late Dr. Presl.+ Of these, that of 
Professor Fée is both the most recent, and the most perfectly and 
carefully digested, but it applies only to the two groups we have 
above distinguished as the Polypodinee and the Oyatheinee, so that 
several of the smaller groups are not included. Another elaborate 
arrangement of still more recent date, is that of Professor Met- 
tenius,§ who does not, however, adopt the modern genera to any 
extent, and whose grouping appears somewhat complicated. 
* Fee, Genera Filicum, Strasbourg, 1850—1852. 
T J. Smith, in Hookers Journal of Botany, iv. 38 et seg. ; London Journal of 
Botany, i. 419 et seg. 
X Presl, Tentamen Pteridographiw, Prague, 1836 ; Hymenophyllacee, Prague, 
1843 ; Supplementum Tentaminis Pteridographie, Prague, 1845 ; Epimeliz Botanice, 
Prague, 1849. 
$ Mettenius, Filices Horti Botanici Lipsiensis, Leipsig, 1856. 

