The Fern Alliance 
of a Selaginella-like club-moss (Lepidodendron Vel- 
theimianum), and one can see the splitting of the spore- 
coat.é 
That such rare and delicate forms of vegetable life 
as fungt, spore-tubes, and the prothallia, which grew in 
Palzeozoic times, have come down to us is sufficiently 
marvellous, yet gives a very deceptive impression of our 
knowledge of the Carboniferous period. 
It is not certain whether the atmosphere was cold or 
a damp, steamy heat. Professor Henslow has tried to 
show that the climate was dry and not damp, but this 
theory has not been accepted by most geologists and 
botanists. Mosses do not seem to have been nearly as 
abundant as one would have thought likely, but the peat- 
mud-like character of what is now coal is like the peaty 
humus of the forests of Valdivia or Punta Arenas in Chile, 
of the summit of Ruwenzori, or even of the oak and birch 
clumps at the edge of a peat-moss in Scotland. 
It was, in the author’s opinion, a damp, still, and 
steamy atmosphere certainly, but not necessarily a very 
hot or even a subtropical climate. 
But the real difficulties and dangers of this chapter 
begin when one tries to give even a sketchy impression 
of the great and important discoveries which have been 
made by many English botanists, who have laboriously 
examined the actual plants which lived in the forests. 
So far we have been, intentionally, as vague as possible 
about them. 
Von Wettstein, in a recent publication,’ sketches in 
a very interesting way the general course of develop- 
ment of the great groups of plants. 
The algze were water-plants. The mosses begin life 
as a green thread-like mass called the protonema, which 
is exactly like an alga and also lives in water. Yet 
their stems are in most cases formed in air. 
83 
