THE FIRST AIR-BREATHERS. 159 



examples are found. ^ But here their reign ceases, and they 

 give place to reptiles of more elevated tyi)e, whose history we 

 must consider in the next chapter. 



Nothing can be more remarkable than the apparently sudden 

 and simultaneous incoming of the batrachian reptiles in the 

 Coal-formation. As if at a given signal, they came up like 

 the frogs of Egypt everywhere and in all varieties of form. If, 

 as evolutionists suppose, they were developed from fishes, this 

 must have been by some suddrn change, occurring at once all 

 over the world, unless indeed some great and unknown gap 

 separates the Devonian from the Carboniferous — a supposition 

 which seems quite contrary to fact — or unless in some region 

 yet unexplored this change was proceeding, and at a particular 

 time its products spread themselves over the world — a supposi- 

 tion equally improbable. In short, the hypothesis of evolution, 

 as applied to these animals, is surrounded with geological 

 improbabilities. 



A remarkable picture of the conditions of Palaeozoic hnd 

 life is presented by the occurrence of remains of reptiles. 

 Millepedes and land-snails in such erect trees .^ that repre- 

 sented in Fig. 140. In the now celebrr'jd section of the 

 South Joggins in Nova Scotia, trees of this kind occur at 

 more than sixty different levels ; but only in one of these have 

 they as yet been found to be rich in animal remains. Fortu- 

 nately this bed is so well exposed and so abundant in trees, 

 that I have myself, within a few years, removed from it 

 about twenty of them, the greater number affording remains 

 of land animals. 



The history of one of these trees may be shortly stated thus. 

 It was a Sigillaria, perhaps two feet in diameter, and its stem 

 had a dense and imperishable outer bark, a soft cellular inner 

 bark liable to rapid decay, and a slender woody axis not very 

 durable. It grew on the surface of a swamp, now represented 

 by a bed oi coal. By inundations and by subsidence, this 

 ^ Mastodonsaurus or La^yrinthodon, 



