466 MESOZOIC TIME — REPTILIAN AGE. 



wards the close of the period, dry-land intervals begin to predo- 

 minate over the marine, and some parts of the Jurassic lands are 

 regions of lakes and estuaries, of forests, and of abundant Eeptile 

 life. The history in Europe in part runs parallel with this, although 

 with many local peculiarities. 



The position of the Jurassic beds across England on the east of 

 the older parts of the island, and their continuation over parts of 

 northern France, correspond with the view that they were formed 

 on the borders of a German Ocean basin. This is well shown as 

 relates to England on the map on p. 354. Whether there was 

 then a British Channel or not is not yet decided. Some English 

 geologists make the channel of Post-tertiary origin. 



Life. — It is evident from the review that, while Conifers and 

 Cycads made up the bulk of the Jurassic forests, — Cestraciont and 

 other Sharks, Rays and Ganoids, the fishes of the world, — Trigonise, 

 Gryphsese, Ammonites, and Belemnites, a characteristic part of the 

 Mollusks, — at the same time grazing and carnivorous Dinosaurs 

 and Crocodilians, huge Swimming Saurians, Flying Lizards, and 

 Turtles, existed in vast numbers, and were the dominant inhabit- 

 ants of the globe. Reptiles were pre-eminent in each of the three 

 elements, — in place of whales in the water, of beasts of prey and her- 

 bivores on the land, and of birds in the air. It was the meridian of 

 the Reptile world. And the abundance and variety of the remains 

 in Britain seem to point to that region as one of the most populous 

 centres in the Reptile world. 



Along with these powerful Reptiles, there were small Marsupials, 

 and probably Insectivores, — announcements of the decline of the 

 Reptile Age, and precursors of the reign of Mammals. 



The great multitudes of Reptile and other remains entombed 

 in the Stonesfield slate, the Wealden, and the beds at Solenhofen, 

 do not indicate an excess of population about these spots. They 

 point out only the places where the conditions were favorable for 

 the preservation of such relics, and prove that the land was covered 

 with foliage and swarming with life, everywhere, we may believe, 

 as regards Insects, and at least in the vicinity of water for Reptiles. 

 A bed of coal is not proof of more vegetation than elsewhere, but 

 of the presence of fresh waters during the accumulation and 

 afterwards, which favored the kind of decomposition required for 

 making coal (see p. 361). 



The dirt-bed of Portland, abounding in Mammalian remains, and 

 yet only five inches thick, shows strikingly what we should find in 

 the Coal formation, with its many scores of dirt-beds of far greater 

 thickness, if Mammals were then living. 



