236 CHAEACIEES OF TRIBES AND GE^'EEA. 



the fronds, they nevertheless all ag-ree in general aspect 

 with Phegoptevis and Lastrea, diifering only in the sori 

 being furnished with a calyciform indusium. 



1'2.5.— Cystopteeis, Bet-ali. (1806). 

 Polypodiiim, Liiiii.; Asjjidium sp. aitct. 



Vernation fasciculate or uniserial. Fronds slender, lan- 

 ceolate, bipinnatifid, 6 to 15 inches high. Veins forked; 

 venules free. Sori punctiform, lateral. Indusium cucal- 

 late, interiorly attached. 



Type. Polopodium fragile, Linn. 



Illust. Hook, and Bauer Gen. Fn.,t. 52, B ; Schott, Gen. 

 FU., fig. 8 ; Moore Ind. Fil., p. 78, A; J. Sm. Ferns, 

 Brit, and For., fig. 76 ; Hook. Syn. Fil., t. 2, fig. 19. 



Obs. — This genus contains low growing Ferns, with the 

 general character of the small species of the Lopliidimn 

 section of Lastrea, but it is technically distinguished by the 

 indusium being short, ovate, or oblong, and vaulted, so as 

 to form a cucnllate marsupial cyst, opening exteriorly. 

 It has also some claims of relationship with Atlnjriurn ; but 

 the base of attachment of the indusium being across the 

 venule — not longitudinally along one side as in that genus 

 — indicates its natural affinity to be with Lastrea,. 



Representatives of this genus are found widely spread 

 over the northern part of Europe, Asia, and America, even 

 to within the Ai-ctic circle, and also in several localities in 

 the southern hemisphere. The different appearances of 

 specimens and observation of living plants from different 

 localities, have given rise to at least twenty species being 

 described by various authors ; but careful examination 

 reduces that number to the following. 



With the exception of C. montarM, all the species have 



