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THE FERN WORLD 
and tlie following species Angulare — the plants in some re- 
spects are so similar as to be frequently confounded — con- 
sists in the rounding of the outer edges of the pinnules, which 
are not angular, as are the pinnules of Angulare. Further 
marks of distinction between this species and Angulare 
are found in the more rigid and prickly looking habit of 
Aculeatum, the darker green of its shining fronds and their 
more leathery texture. The venation consists of a mid- 
vein through the centre of each pinnule, with alternate 
branched veins upon which are borne the round clusters of 
spore cases. These are usually found ranged in short lines 
along on each side of the mid-veins of the pinnules. Each 
cluster is covered by a round indusium attached by a short 
stem on its under side. The fructification, however, is 
usually confined to the upper half of the backs of the frond. 
There are about twenty variations from the normal form of 
this handsome Fern. 
Distribution. — The Hard Prickly Shield Fern has a wide 
range throughout Europe, occurring in Austria, Belgium, 
France, Germany, Greece, Holland, Portugal, Russia, 
Scandinavia, Spain, Switzerland, and Turkey. It is found 
in the Island of Madeira, in the north and in the south of 
Africa, in Asia, and — though somewhat rare — in North 
America. In England it occurs in the following counties, 
namely : — Bedford, Berks, Bucks, Cambridge, Chester, 
Cornwall, Cumberland, Derby, Devon, Dorset, Durham, 
Essex, Gloucester, Hants (including the Isle of Wight), Here- 
ford, Hertford, Kent, Lancaster, Leicester, Lincoln, Mid- 
dlesex, Monmouth, Norfolk, Northampton, Northumberland, 
Nottingham, Oxford, Salop, Somerset, Stafford, Suffolk, 
Surrey, Sussex, Warwick, Westmoreland, Wilts, Worcester, 
and York. It is found also in the Isle of Man. In Wales 
it is distributed through the counties of Anglesea, Breck- 
nock, Carnarvon, Carmarthen, Denbigh, Glamorgan, and 
