182 
THE GEOLOGIST. 
branclies fell off in myriads, with fi-uits, and catkins, and seeds, they 
formed a matted mass in the sluggish water. 
On the stumps of the decaying trees the ferns would grow, and I 
have seen markings on a Sigillaria which induce me to believe this 
was really the case ; and the hollow trees would form a safe retreat 
for such wingless insects, snails, or lizards, as the forest possessed. 
Lest this should be thought a wholly anomalous state of things, 
we have, as an instance, the mangrove swamps of tropical countries, 
where, in the saltwater lagoons, whole forests of trees gTow, among 
whose roots fish and Crustacea find protection, and sea-shells are 
abundant. A species of oyster is commonly attached to the stems 
and the submerged branches. And if the TJnio of the coal must be 
regarded as an TJnio, there are even kinds of this genus which live in 
these putrid swamps. 
For it must not be supposed that the trees gTew in an open sea. 
Shallow tracts, shut out from the main ocean by spits of sand and 
sandbanks, and scarcely, if at all, subject to tides, are the state of 
things that prevail in many a lagoon now ; and in all probability 
such was the case in the coal epoch. In such localities it might be 
expected that we should find creatures admirably adapted to their 
habitation, but unlike the ordinary denizens of sea or lake. The 
quantity of decaying vegetation would give a black colour to the 
mud, and coal shales are very black indeed : occasional currents 
would bring sand from seaward, and sandstones are common things 
in the coal-formation. If the ocean got free entry for a while, we 
should have colonies of true sea animals (the Goniatites and Avicula 
before mentioned), and such do every now and then occm*. But the 
ordinary inhabitants of these delightfal muddy creeks, half smothered 
in a thick forest of water-loving plants, would be the shells and 
Crustacea suited to the locality, i. e., the Antliracosia or TJnio and the 
Limulus. Crowds of minute water-fleas (Cypris and Cy there), such 
as live in stagnant waters now, are found in the coal-measures. 
Thousands of worms, of all sizes, burrowed in the silt, and revelled 
in the feast of fat things that were putrifying there. 
I believe this picture gives the true aspect of the dank and lux- 
uriant vegetation, flourishing in a sullen steaming atmosphere heavy 
with miasmatous vapom's ; uncheered by the song of birds, scarcely 
musical with the hum of insects, and varied by no flowers, no trees 
yielding fruit, whose seed was in itself! Such a habitation was not fit 
for man — not even for the quadrupeds he delights to call his own. 
It was the ground-plan and first outline only of a picture, to be filled 
up dui'ing succeeding geologic times, and exquisitely finished before 
man was placed upon the earth. 
What efiect must all this mass of vegetation have produced on the 
surrounding air and water ? Plants, we know, are chiefly formed of 
carbon, taken into their substance from the air and water, under the 
form of carbonic acid. They have the power of secreting the car- 
bon from it, and they set free the oxygen for the use of animals. 
So that an atmosphere in a confined spot is actually purer — more 
