266 BIO ANIMALS 



thus introduced, and still later, in spite of the struggle for 

 life against the huge modern cetaceans (the true monarchs 

 of the recent seas), the sharks continued to hold their own 

 as producers of gigantic forms ; and at the present day 

 their largest types probably rank second only to the whales 

 in the whole range of animated nature. There seems no 

 reason to doubt that modern fish, as a whole, quite equal 

 in size the piscine fauna of any previous geological age. 



It is somewhat different with the next great vertebrate 

 group, the amphibians, represented in our own world only 

 by the frogs, the toads, the newts, and the axolotls. Here 

 we must certainly with shame confess that the amphibians 

 of old greatly surpassed their degenerate descendants in our 

 modern waters. The Japanese salamander, by far the 

 biggest among our existing newts, never exceeds a yard in 

 length from snout to tail ; whereas some of the labyrin- 

 tliodonts (forgive me once more) of the Carboniferous Epoch 

 must have reached at least seven or eight feet from stem to 

 stern. But the reason of this falling off is not far to seek. 

 When the adventurous newts and frogs of that remote 

 period first dropped their gills and hopped about inquir- 

 ingly on the dry land, under the shadow of the ancient 

 tree-ferns and club-mosses, they were the only terrestrial 

 vertebrates then existing, and they had the field (or, rather, 

 the forest) all to themselves. For a while, therefore, like 

 all dominant races for the time being, they blossomed forth 

 at their ease into relatively gigantic forms. Frogs as big 

 as donkeys, and efts as long as crocodiles, luxuriated to 

 their hearts' content in the marshy lowlands, and lorded it 

 freely over the small creatures which they found in undis- 

 turbed possession of the Carboniferous isles. But as ages 

 passed away, and new improvements were slowly invented 

 and patented by survival of the fittest in the offices of 

 nature, their own more advanced and developed descend- 



