580 



CYIII. POLYPODIACE^. 



[ Ceterach. 



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11, Blechnum. Sori linear, parallel on each side of the midrib, distant 



from the margin. Tab. x. f. 6. 



12. Adiantum. Sori oblong or roundish" marginal. Involucres formed 



of the refiexed margins or lobes of the frond, and bearing the cap- 

 sules. Tab. X. f. 7. 



B. Capsules opening irregular!]/, placed on a receptacle at the margin of 



the frond and terminating a vein ; their ring horizontal, 



t 



13, Trichomanes. Sori marginal. Involucre monophyllous, subcyliu- 



drical, surrounding a much elongated receptacle bearing the cap- 



♦ sules. Tab. x. f. 8. 



14. IlYMENorHYLLUM. Sori marginal. . Involucre monophyllous, 



2-valved, including an elongated receptacle bearing the capsules. 

 Tab. xi. f. 1. ' ■ ' 



A. Capsules opening transversely^ placed on the hack of the frond 



but sometimes close to its margin ; their ring vertical^ usu- 

 ally incomplete. Cellular tissue of the frond compact} 

 PoLYroDiEiE. (Gen. 1 — 11.) 



1. Ceterach Willd. Ceterach. (Tab. IX. f. 1.) 



Sori oblong or linear straight, scattered, arising from reticu- 

 lated veins, covered (as is the whole back of the frond) with 

 chaffy scales. Involucre none (or obsolete). — Name : from the 

 Celtic cedor wrach^ double rake; in modern Gaelic also ceither 

 is four^ and rac rake. . 



1. C. officindrum Willd. (common C); fronds pinnatifid co- 

 vered beneath with imbricated chaffy scales, segments ovate 

 obtuse, scales entire. Grammitis Ceterach Sw. Scolopendrium" 

 E. B, t. 1244. Asplenium Z. 



Rocks and walls, most abundant in limestone countries, and the 

 south of England and Ireland. Rare in Scotland ; near Perth, 

 Paisley and Glasgow ; walls about Drumlanrig, Dumfriesshire ; Kil- 

 finnan, Argyleshire, — Mr, W. Wilson finds evident traces of an in- 

 volucre on the lower side of the sorous, viz, " a nairrow membrane, 

 fringed with the same chaffy scales which cover the back of the 



frond ; " and the same is figured in Bauer and Hooker's Genera of 

 Ferns, p. 113. a. 



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2. Gymnogramme Desv. Gymnogramme. 

 Sori oblong or linear on forked free veins, not covered with 



r 



m 



1 The compactness of the tissue arises, not only from the small size of the cel- 

 lules, but also from there being several in the thickness of the frond, giving it a 

 certain degree of opacity : in the next group (B.), the cellular tissue is lax and 

 almost transparent, from the larger size of the cellules, and there being often oaly 

 one in the thickness of the frond, in this respect resembling the leaves of most 

 Mosses, but differing from them by having the nerves and veins composed of that 

 kind of vascular tissue called ducts, to which it were well to restrict the term 

 ansieiickpma. 



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