BIO ANIMALS 267 



ants, the reptiles and mammals, got the upper hand with 

 them, and soon lived them down in tho strug^^le for life, so 

 that this essentially intermediate form is now almost en- 

 tirely restricted to its one adapted seat, the pools and 

 ditches that dry up in summer. 



The reptiles, again, are a class in which the biggest 

 modern forms are simply nowliere beside the gigantic 

 extinct species. First appearing on the earth at the very 

 close of the vast primary periods — in the Permian age — 

 they attained in secondary times the most colossal propor- 

 tions, and have certainly never since been exceeded in size 

 by any later forms of life in whatever direction. But one 

 must remember that during the heyday of the great 

 saurians, there were as yet no birds and no mammals. 

 The place now filled in the ocean by the whales and gram- 

 puses, as well as the place now filled in the great conti- 

 nents by the elephants, the rhinoceroses, the hippopotami, 

 and the other big quadrupeds, was then filled exclusively 

 by huge reptiles, of the sort rendered familiar to us all by 

 the restored effigies on the little island in the Crystal Palace 

 grounds. Every dog has his day, and the reptiles had 

 tlieir day in the secondary period. The forms into which 

 they developed were certainly every whit as large as any 

 ever seen on the surface of this planet, but not, as I have 

 already shown, appreciably larger than those of the biggest 

 cetaceans known to science in our own time. 



During the very period, however, when enaliosaurians 

 and pterodactyls were playing such pranks before high 

 heaven as might have made contemporary angels weep, if 

 they took any notice of saurian morality, a small race of 

 unobserved little prowlers was growing up in the dense 

 shades of the neighbouring forests which was destined at 

 last to oust the huge reptiles from their empire over earth, 

 and to become in the fulness of time the exclusively 

 18 



