106 THE HISTORY OF CREATION. 
was already developed during the paleeolithic period out of 
other ferns by adaptation to an aquatic life. 
The fourth class of ferns is formed by the Tongue Ferns 
(Ophioglossze, or Glossopterides). These ferns, to which 
belongs the Botrychium, as well as the Ophioglossum 
(adder’s-tongue) of our native genera, were formerly con- 
sidered as forming but a small subdivision of the frondose 
ferns. But they deserve to form a special class, because 
they répresent important transitional forms from the 
Pterideee and Lepidophytes towards higher plants, and 
must be regarded as among the direct progenitors of the 
flowering plants. 
The fifth and last class is formed by the Scale Ferns 
(Lepidophytes, or Selagines). In the same way as the 
Ophioglossze arose out of the frondose forms, the scale ferns 
arose out of the Ophioglosse, They were more highly 
developed than all other ferns, and form the transition to 
flowering plants, which must have developed out of them. 
Next to the frondose ferns they took the largest part in the 
composition of the paleolithic fern forests. This class also 
contains, as does the class of reed ferns, three nearly related 
but still very different orders, of which only one now exists, 
the two others having become extinct towards the end of 
the carboniferous period. The scaled ferns still existing 
belong to the order of the club-mosses (Lycopodiacez). 
They are mostly small, pretty moss-like plants, whose 
tender, many-branched stalk creeps in curves on the ground 
like a snake, and is densely encompassed and covered by 
small scaly leaves. The pretty creeping Lycopodium of 
our woods, which mountain tourists twine round their 
hats, is known to all, as also the still more delicate 
