34 
BRITISH FERNS. 
perfection on its native rocks, in the open air in Ire¬ 
land, Scotland, or Wales. In the south of England it 
seldom thrives, and, on this account, is best left out 
of a growing collection of ferns. 
The groups of ferns now called Nephrodium was 
formerly known as A spidium, afterwards as Lastrea — 
but we have adopted the most recent name according 
to modern botanists. Its distinguishing charaoteristic 
is a notch in the otherwise round involucre which 
changes the simple circle into a heart or kidney-snape. 
Many of the largest and most elegant ferns belong 
to this group. Nephrodium is from a Greek word 
signifying kidney, in allusion to the form of Ine 
involucre. 
CRESTED BUCKLER FERN. 
NEPHRODIUM CRISTA TUM t 
Swartz, Smither, Hooker. 
(Plate III. Fig. I.) 
SYNONYMS. 
Aspidium cristatum , Swartz, 
Smith. 
Lastrea cristata , Babington, 
Presl, Moore. 
Polypodium cristatum, Linnaeus. 
Polypodium Callipteris , Ehrhart. 
Lophodium Callipteris , Newman. 
This fern is not very common in England, but is easy 
to distinguish from other species. It is more prized 
for its rarity than its elegance. The fronds are but 
few in number, and rise from the crown of each grow¬ 
ing branch of the rhizome, which is stout and strong* 
