AGE OF FISHES. 203 



and heads of crinoids. Among them is seen a species 

 of the family Favosites, having a beautiful honey-comb 

 structure, and appearing in 

 masses in some cases of not 

 less than five feet in diameter. 

 A species of this family is rep- 

 resented in Fig. 112. The ele- 

 gant chain coral, Fig. 104, is 

 also present in this locality. 



294. Variety in Rock-making at the same Period. 

 Different kinds of rock-making were sometimes going on 

 at the same time over different parts of the Devonian 

 area in this country, and the same is true of other coun- 

 tries also. Thus, at one period, while corals, crinoids, 

 etc., were accumulating limestones over a large area in 

 the Western States, over New York there were exten- 

 sive flats forming and solidifying into sandstones, and 

 shales, and flags. Here are found ripple-marks and 

 shrinkage cracks, showing that the flats were sometimes 

 covered with shallow water, and sometimes drying in 

 the sun. The ripple-marks in the flags are so even and 

 extensive that it is obvious that the sea swept over wide- 

 spread flats. While this was going on in New York, 

 there was at the West, where the corals and crinoids 

 were building limestone, an interior sea of vast extent, 

 and of suitable depth for these animals to flourish in. 



295. Devonian Vegetation. In the age of Fishes there 

 was not only more marine vegetation than in the age of 

 Mollusks, but land vegetation appeared, and before the 

 middle of the age had passed it had covered the com- 

 paratively small portions of the continents that had fairly 

 risen above the ocean and remained so. At the close of 

 the age the State of New York, although it had been 

 previously submerged, formed a part of the land which 

 was thus covered. The plants, as we approach the con- 

 clusion of this age, become more and more like those of 

 the next age, thus exemplifying that foreshadowing of 



