144 BRITISH FERNS. — SUB-ORDER II. TRIBE 10 . 
duous. The normal form is distinct in appearance from all other 
species. 
Varieties. 
i. Clintonianum, Birkenhead. A North American variety. 
Length, 3 feet. 
*2. contluens, Lowe (cristatum-confluens, Clapham). Found by 
myself, on Oxton Bogs. Normal in size ; pinnae confluent. 
3. Floridanum, Birkenhead. A large-grower, from Florida. 
4. spinulosum, Moore. Basal pinnae more remote and larger, 
and more nearly like some of the forms of “spinulosum.” It is a 
much more common form, growing in damp boggy places, and 
sometimes in woods. 
5. uliginosum, Moore. More linear-lanceolate, with oblong acute 
pinnules. Only found growing in boggy situations, mostly amongst 
plants of the normal form. 
THE RIGID BUCKLER FERN. 
N ephrodium RIGIDUM. — Desvaux. 
(Lastrea rigida. — Presl .) 
Another mountain fern ; with dull-green fronds of from 1 to 
2 feet high ; somewhat lanceolate, bipinnate, and scented. Not 
easily confounded with any other species. It has been found 
in Cornwall, also in Yorkshire (Wharnside, near Ingleburgh, and 
near Settle) ; in Westmoreland (Arnside, Farleton, and on Hutton 
Roof Crags) ; and in North Lancashire. It is a native of France, 
Germany, Switzerland, Sardinia, Italy, Sicily, Dalmatia, Hungary, 
Russia, Siberia, and Asia Minor. 
A deciduous species, confined to limestone mountains at heights 
ranging from 1200 to 1500 feet. 
Varieties. 
1. abruptum, Lowe. Found at Whitbarrow, by Mr. J. M. Barnes. 
An abrupt-ended variety. 
2. argutum, Birkenhead. A North American variety. Fronds 
smoother and more triangular. 
3. cristatum, Barrand. Found recently. Small crests through- 
out the frond. Mr. Druery possesses this plant. 
4. interruptum, Barnes. Found at Arnside, by Mr. J. Cross- 
field. An interrupted form. 
5. polyclados, Moore. Found at Farleton Knott, by Mr. J. M. 
Barnes, and at Crosby Ravensworth, by Mr. Clarke. Fronds 
divide into two, either at the base or higher up. 
6. ramosum, Lowe. Received from Mr. Clarke’s gardener, at 
Floss House, Crosby Ravensworth, Westmoreland. It differs in 
two fronds rising from one stem. Another variety , polyclados, 
found at Arnside, only differs in having the frond sometimes 
dividing in the upper parts as well as at the base. This form 
was sent to me in 1863, and it is still in my fernery, and has 
retained its branching habit. More dwarf than the normal form. 
