CRETACEOUS PERIOD. 481 



the Atlantic on the west; but farther south they occur at the deep indentation 

 of the Bay of Biscay. They cover part of the Pyrenees, and reach into Spain 

 in what has been called the Pyrenean basin, which in the Cretaceous period was 

 a bay on the Atlantic. There is another sea-border deposit at Lisbon, in Spain. 

 In southern France, over what is called the Mediterranean basin, the beds ex- 

 tend from the Gulf of Lyons along the Mediterranean coast, northeast to Swit- 

 zerland, though with interruptions. The formation is found in the Juras and 

 Alps, in Italy, Savoy, Saxony, Westphalia and Bohemia, northern Germany, 

 Poland, middle and southern Russia, Greece, and other places in Europe. In 

 Asia it has been observed about Mount Lebanon and the Dead Sea, the Cauca- 

 sus, in Circassia and Georgia, and elsewhere; in northern and southern Africa; 

 in South America, along the Andes, and on the Pacific coast, occurring in 

 Venezuela, in Peru, at Concepcion in Chili, in the Chilian Andes at the passes 

 of the Portillo and Rio Volcan at an elevation of 9000 to 14,000 feet, in the 

 Straits of Magellan at Fort Famine in Fuegia. 



II. Life. 



The Life of the Cretaceous period in Europe resembled that of 

 America, but was far more abundant. Nearly 6000 species of ani- 

 mals have been described, more than half of them Mollusks ; 

 whereas in America the whole number does not exceed 2000. 



1. Plants. 



Angiosperms and Palms were growing in Europe, and among the 

 former there were the Willow, Walnut, Maple, and Holly. But 

 the relics of Ferns, Conifers, and Cycads greatly preponderate ; for 

 the Cretaceous was properly the closing part of the era of Cycads. 

 Vegetable remains of all kinds are rare, as the deposits are marine. 



The microscopic Protophytes called Diatoms and Desmids are 

 found in some of the beds, especially in the flint of the Chalk. 

 The former have siliceous cases, as explained and illustrated on 

 p. 271, and they may have contributed, as has been suggested, to 

 the material of the flint nodules. The Desmids are not siliceous, 

 but are still very common in the flint, — far more so than Diatoms 

 (which are rare) : the kinds which have been called Xanthidia are 

 especially abundant ; their forms are very similar to those from 

 the Devonian hornstone figured on p. 271. 



2. Animals. 

 The Protozoans of the family of Khizopods (p. 163) appear to have 

 been among the most important rock-making species of the Creta- 

 ceous period ; for it is supposed that the Chalk itself is to a large 

 extent made of their shells. According to Ehrenberg, a cubic inch 



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