152 
HISTORY OF BRITISH FERNS. 
but perhaps, from their crowded position, preventing its 
proper formation. 
The name Ceterack is said to be an alteration of the 
word Chetherak^ which was applied to this plant by 
Persian and Arabian medical writers. 
Ceterach officinarum, Willdenow. 
The Scaly Spleenwort, or Common Scale Fern, 
(Plate I. %. 1.) 
A dwarf, evergreen, distinct-looking, and very pretty 
Fern, growing in tufts. The fronds when fresh are thick 
and fleshy, and from this cause they are perfectly opaque 
when dry. Their size varies according to the circum- 
stances of their growth, from two to six inches in length, 
rarely exceeding the latter. They grow on a short scaly 
stipes, and are either pinnatifid, as is commonly the case, 
or more rarely pinnate, the difierence being, that in the 
latter the fronds are divided rather more deeply than in 
the former. The upper surface is a deep opaque green ; 
and the under surface is densely crowded with rust- 
coloured brown closely-packed overlapping scales, which, 
being just seen projecting from the margin, and still more 
fully in the exposed under-surface of the young partially- 
