THE ADDERS-TONGUE 
247 
to the stem, ancl the fruitful spike runs up perpendicularly, 
bearing its spore cases at its top. The barren portion of the 
frond, however, is not divided as in the Moonwort into a series 
of stalked pinnules, but is a simple egg-shaped or pear-shaped 
leaf, both stem and leaf being of a vivid green. The venation 
of this leaf is very beautiful, consisting of a system of anas- 
tomosing veins, forming a complete network over the sub- 
stance of the leaf. The spore cases at the top of the fruit 
spike are ranged in a double row, one on each side of the stem, 
within about an inch of its apex, and they are rounded in 
form containing the almost impalpable dust-like spores. 
When the latter are ripe these cases split open transversely, 
and have then the appearance of a double row of teeth or of 
separate fangs. Hence the name Ophiojlossum, which is 
derived from ophios, ‘ a serpent,’ and glossa, ‘ a tongue.’ The 
specific name vulgatum is applied on account of the abundance 
of this little Fern. The height to which the fronds grow is 
from three or four to about twelve inches, and the undivided 
stem or stipes is sometimes half the entire length of the frond, 
sometimes more than half, and sometimes less. No departure 
from the normal form of the common Adders-tongue has ever 
been discovered in Britain. 
Distphbution.— Throughout Europe this Fern is widely 
distributed. It also is found in Africa, at the Cape of 
Good Hope ; in Asia, in the Caucasian Mountains, in the 
East Indies, in Kamtschatka and in Siberia; as well as 
in North America and Mexico ; in Australia and New 
Zealand. 
In the British Islands it is most common in England ; 
being found — sometimes in vast quantities, covering many 
acres of ground— in the counties of Bedford, Cambridge, 
Chester, Cornwall, Cumberland, Derby, Devon, Dorset, 
Durham, Essex, Gloucester, Hants (including the Isle of 
Wight), Hereford, Hertford, Huntington, Kent, Lancaster, 
Q 2 
