154 THE BRITISH FERNS. 
30. dubium (Woll.). This is a thick harsh form, more rigid than 
usual, with much of the aspect of P. aculeatum, having also an 
enlarged anterior basal pinnule as in that species. The form and 
attachment of the lower pinnules, however, unites it with the present 
species, of which it may be regarded as a form approaching P. 
aculeatum. Sussex, G. B. Wollaston. We regard the following as 
being the same form :—Hampshire : Basingstoke, F. Y. Brocas. 
Wiltshire: Salisbury, W. Moore. Somersetshire: Nettlecombe, 
C. Elworthy. Lancashire: Wood Plumpton, T. Stansfield. Den- 
bighshire: Rhuabon, A. L. Taylor. Antrim, Ireland, D. Moore. 
31. plumosum (Woll.). This is one of the most beautiful of the 
varieties of this charming fern. The fronds are rather large, pale- 
green, broad, having an ovate-lanceolate outline, bipinnate, becoming 
almost tripinnate in the most divided parts, thin and dry in texture, 
becoming papery when dry. The pinnules are long-stalked, deeply 
inciso-lobate, and give a feathery aspect to the gracefully arching 
fronds, which well deserve the name plumosum. The thin texture 
and deep cutting of the parts are the most important characteristics. 
The basal anterior lobe of the pinnules is large, forming the usual 
auricle, and this is lobed on the margin, or biserrate with sharp teeth, 
the other parts being deeply incised, each lobe directed forwards, 
and again cut into sharp-pointed teeth. The rachis of the pinne is 
very slender. It was found in—Devonshire : near Ottery St. Mary, 
G. B. Wollaston; Barnstaple, C. Jackson. Somersetshire: Nettle- 
combe, C. Elworthy. [Plate XX F.] 
Mr. Jackson has also found, near Barnstaple, a form evidently 
allied to this, and probably an accidental variation of it, in which 
the lobes on the posterior side of the posterior pinnules are sepa- 
rated into distinct linear toothed pinnulets; the pinnules on the 
. lower side of the rachis being in fact deorsely-pinnate (deorso- 
pinnatum). It is an extremely elegant variation, but we fear not 
permanently distinct from plumosum ; it requires further trial. 
32. ornatum (M.). This variety is very ornate in character. 
The frond is of the normal outline, as also are the pinne. The 
pinnules are rather crowded, ovate, with a very large anterior 
auricle ; deeply lobed, the lobes spreading and having rather open 
er distinctly marked sinuses, distinctly biserrate, and the auricle 

