CKNOZ01C PAl A, AGE OF MAMMALS. 



But if these highest plants were exceptionally abun- 

 dant, so were also the lowest of all, viz., the unicelled 



FIG. 323. 



FIG. 327. 



FIG. 328. 



FIG. 330. 



FIG mi. 



FIG. 332. 



FIGS. 327-332. American Tertiary plants (after Safford and Lesquereux): 327. Quer- 

 cus crassinervis. 328. Andromeda vaccinifoliae affinis. 329. Carpolithes irregu- 

 laris. 330. Fagus ferruginea nut. 331. Fruit of Sequoia Langsdorfii (after 

 Heer). 332. Leaf of Sequoia Langsdorfii (after Heer). 



diatoms. The great deposits of diatomaceous earths 

 found in many parts of the world are Tertiary. In the 

 United States the best known localities are near Eich- 

 mond, Virginia, and in California. These deposits are 

 many miles in extent, and thirty to one hundred feet 

 thick, and made up wholly of the silicious shells of these 

 microscopic plants. 



LE CONTE, GEOL. 24 



