THE OLDEST AIR-BREATHERS 301 



millipedes, and perhaps insects. The air-breathing vertebrates 

 are not intended to consume the exuberant vegetable growth, 

 but to check the increase of its animal enemies. Plant life 

 would thus seem to have had in every way the advantage. 

 The miUipedes probably fed only on roots and decaying sub- 

 stances, the snails on the more juicy and succulent plants 

 growing in the shadow of the woods, and the great predomi- 

 nance of the family of cockroaches among carboniferous insects 

 points to similar conclusions as to that class. While, moreover, 

 the vegetation of the coal swamps was most abundant, it was 

 not, on the whole, of a character to lead us to suppose that it 

 supported many animals. Our knowledge of the flora of the 

 coal swamps is sufficiently complete to exclude from them any 

 abundance of the higher phaenogamous plants. We know 

 little, it is true, of the flora of the uplands of the period ; but 

 when we speak of the coal-formation land, it is to the flats only 

 that we refer. The foliage of the plants on these flats with the 

 exception of that of the ferns, was harsh and meagre, and there 

 seem to have been no grasses or other nutritious herbaceous 

 plants. These are wants of themselves likely to exclude many 

 of the higher forms of herbivorous life. On the other hand, 

 there was a profusion of large nut-like seeds, which in a modern 

 forest would probably have afforded subsistence to squirrels 

 and similar animals. The pith and thick soft bark of many of 

 the trees must at certain seasons have contained much nutri- 

 tive matter, while there was certainly sufficient material for all 

 those insects whose larvae feed on living and dead timber, as 

 well as for the creatures that in turn prey on them. It is re- 

 markable that there seem to have been no vertebrate animals 

 fitted to avail themselves of these vast stores of food. The 

 question : " What may have fed on all this vegetation ? " was 

 never absent from my mind in all my explorations of the Nova 

 Scotia coal sections ; but no trace of any creature other than 

 those already mentioned has ever rewarded my search. In 



