THE COMMON MAIDENHAIR SPLEENWORT 
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to the margins of each pinna, and the oblong sori, covered 
when young by their oblong indusia, are produced upon the 
veins well within the margins of the pinnae, which are often 
somewhat curled or bent under, having thus a peculiar 
concave appearance. When the indusia are thrown off by 
the development of the spore cases, the sori. frequently 
become confluent in two lines, one on each side of the mid- 
vein of each pinna. Sometimes, though not very frequently, 
the opposite lines unite, and then the sori are confluent over 
the whole of the central part of the under surface of the 
pinnae. There are more than thirty variations from the 
normal form of the present species. 
Distribution. — This Fern has a very wide range over the 
surface of the world. On the continent of Europe, it is an 
inhabitant of Belgium, Corsica, the Crimea, Croatia, Dal- 
matia, France, Germany, Greece, Hungary, Italy, Portugal, 
Eussia, Scandinavia, Sicily, Spain, Switzerland, and Tran- 
sylvania. It occurs in the Azores, and the Cape de Verd 
islands, and in the island of Madeira ; in the Caucasian, the 
Altai, and the Ural Mountains, in Affghanistan, in the Hima- 
laya Mountains, in Cashmere, and in Simla. Also in Algeria 
and Caffraria, the Sandwich Islands, Canada, the United 
States of America, Mexico, Peru, Venezuela, Cuba, Jamaica, 
Australia, and Tasmania. In England this species is found — 
often in very great abundance — in the counties of Bedford, 
Bucks, Cambridge, Chester, Cornwall, Cumberland, Derby, 
Devon, Dorset, Durham, Essex, Gloucester, Hants (including 
the Isle of Wight), Hereford, Hertford, Kent, (including the 
Isle of Sheppey), Lancaster, Leicester, Monmouth, Norfolk, 
Northumberland, Nottingham, Oxford, Rutland, Salop, Som- 
erset, Stalford, Suffolk, Surrey, Sussex, Warwick, Westmore- 
land, Wilts, Worcester, and York ; and also in the Isle of Man. 
In Wales it is found in the counties of Anglesea, Brecknock, 
Carmarthen, Carnarvon, Denbigh, Glamorgan, Merioneth, 
