

CHAPTER V. 
SYNOPTICAL TABLE OF GENERA. 
Tue few genera which are represented among the British Ferns, 
afford so inadequate an illustration of any particular system of clas- 
sification, that their sequence becomes altogether unimportant. In 
our Index Filicum we have attempted an arrangement of the entire 
family of Ferns, on the plan which has been explained in the fore- 
going pages; and this arrangement we follow here in its leading 
features, that is, in so far as respects the principal groups; but as 
regards the sectional subdivisions of these groups, which give the 
actual sequence of genera, it will be more convenient here to follow 
the order adopted in other works on British Ferns, especially 
in our Handbook of British Ferns, and in the Folio edition of the 
present work. The sectional groups are the same as those of the 
Index Filicum, their relative position only having been changed. 
NATURAL ORDER POLYPODIACEZ, or TRUE Ferns. 
The Ferns belonging to this Order have their fronds circinate in 
vernation; their fruetification dorsal or marginal; and their spore- 
cases furnished with an elastic jointed ring. 
* SPORE-CASES NOT VALVATE. 
Trier I.—Polypodinese.—Fructification dorsal ; spore-cases without valves, 
bursting irregularly and transversely ; ring vertical, nearly complete. 
$ 1. —Porvyroprgz.—Sor? round, naked, i. e. without proper indusia or scale- 
like covers, dorsal on the veins. 
1. Polypodium.—Sori punctiform, round or roundish, exposed on _ 
the plane under surface of the frond. 

