
14 THE BRITISH FERNS. 
often deflexed, sometimes approximate sometimes distant above; 
linear-oblong, broadest at the base, gradually narrowing to a point. 
Pinnules oblong, or narrow-lanceolate, flat, obtuse or acute; sessile 
with a broad attachment; decurrent and confluent at the base; or 
with a very short narrowed stalk-like attachment; pinnatifid with 
shallow 2-3-toothed lobes at the base and simple teeth towards the 
apex, or deeply pinnatifid throughout with the lobes variously 
toothed, the teeth confined to the apices of the lobes, or extending 
along their sides, usually short and blunt-pointed, but sometimes 
lengthened and acute, though never normally bristle-pointed. The 
pinnules are sometimes merely patent, but they not unfrequently 
form a right angle with the secondary rachides ; and while in some 
forms there is no appreciable difference in the proportionate size-of 
the lobes, in others the lowest anterior lobe is considerably longer, 
giving the pinnules an auriculate appearance, the enlarged lobes 
forming a conspicuous line on each side the rachides of the pinne. 
Venation of the pinnules, in the less divided forms, consisting of 
a flexuous costa or midvein, producing alternate veins ; the lower of 
these are forked, a venule being directed into each tooth ; the upper 
are simple, directed into the simple teeth at the apex of the pinnules. 
In these less divided forms, the anterior venule of each fascicle bears 
the sorus along its anterior side. When the pinnules are more 
divided, the veins from the costa are pinnately branched, several 
alternate venules being produced, the number corresponding with the 
number of teeth ; the anterior venule is here also soriferous, so that 
a line of sori is produced on each side the costa, but in addition 
some of the other venules of the lower lobes bear sori. When the 
pinnules become very deeply divided, as in the most compound states 
of the plant, each vein produces several fertile venules, and the sori 
then form two lines along the lobes. The veins and venules terminate 
in a slightly attenuated point just within the apex of the tooth 
towards which they are directed. 
Fructification on the back of the frond, dispersed over the whole 
under surface. Sori numerous, short, indusiate, medial ; usually 
occupying the anterior side of the anterior venules in the less 
divided forms, and then often straight and oblong, but the receptacle 
of the lowest one (or more) generally crosses the venule and forms a 

