CRETACEOUS PERIOD. 



471 



1. Plants. 



Angiosperms and Palms were growing in Europe ; and, among the 

 former, there were the Magnolia, Myrtle, Willow, Walnut, Maple, Fig, 

 and Holly, besides a Redwood (Sequoia) and a Palmacites. The 

 relics of Ferns, Conifers, and Cycads still preponderate ; for the Cre- 

 taceous was properly the closing part of the era of Cycads. Vegetable 

 remains of all kinds are rare, as the deposits are mostly 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. 135, 

 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. 257. The microscopic Coccoliths, alluded to on p. 135, 

 have been detected in Chalk. 



2. Animals. 



Foraminifers, or the shells of Rhizopods, are the principal material 

 of the Chalk. According to Ehrenberg, a cubic inch of it often con- 

 Figs. 856-859. 

 858.^ 859 



Rhizopods. — Fig. 856, Lit; lola nautilnidea ; 857, a, Flabellina rugosa; 858, Chrysalidina gradate ,• 

 869, a, Cuueolina pavonia. 



Figs. 860, 861. 





O^ 



Sponge, Fig. 860, Siphonia lobata. Fig. 861 a-h, Sponge Spicules. 



tains more than a million of microscopic organisms, among which far 

 the most abundant are these Rhizopods. Some of the species are 

 represented in Figs. 856-859. 



