AGE OF COAL. 



229 



the carboniferous scenery were heightened by the ab- 

 sence of all running and flying animals. As to sounds, 

 " there was no music in the groves," says Dana, " save, 

 perhaps, that of insect life and the croaking Batrachian." 

 330. Coral Animals. The r^ef-making animals, some 

 varieties of which you see in Fig. 131, were busy wher- 



1. Syringopera. 2. Lythoetrotion. 

 Inm. 6. Ptilopora. 7. Archimedopora 



Aulopora. 4. Amplexus. 5. Clisiophyl- 



Fig. 131. 



ever limestone was forming. They had a large work to 

 do, then, in the sub-carboniferous period, when the great 

 limestone floor was laid down for the coal-measures, and 

 afterward, also, in the case of those strata over the coal- 

 beds which are composed of limestone. 



331. Crinoids and Sea-urchins. These animals abound- 

 ed in connection with the corals, the crinoids being much 

 more abundant than the corals in the limestone of the 

 sub-carboniferous period. Indeed, whole strata are com- 

 posed of the calcareous remains of the crinoids. Two 



