FAUNA OF THE CARBONIFEROUS AGE. 



391 



iferous, while most of the fresh- water and la ad animals are from the 

 Coal-measures. We can notice only what important families are going 



Fig. 520. 



Fig. 522. 



Figs. 520-522.— Carboniferous Corals: 520. Lithoetrotion Calif orniense (after Meek). 521. Cli- 

 siophyllum Gabbi (after Meek). 522. a, Archimedes Wortheni (after Hall); b, portion of same, 

 enlarged to show structure. 



out, what important families are coming in, and a few which are very 

 characteristic. We shall dwell only on what bears on the progress of 

 life. 



Among corals the same general characteristic Palaeozoic type (Quad- 

 ripartita) continues to prevail, though in greatly-diminished variety 

 of families ; for the Favositidas and Halysitidae have passed away, and 

 only the Cyathophylloids, or cup-corals, remain. The most beautiful 

 and characteristic are the Columnar Lithostrotion (Fig. 520), a polyp- 

 coral, and the curious corkscrew-like Archimedes (Fig. 522), a Bryozoan. 



Among Crinoids, the Cystids no longer exist, for they passed out 

 with the Silurian, but the Blastoids and Crinids (Figs. 523-530) in- 

 crease in number and beauty. Also among free Echinoderms the As- 

 teroids (Fig. 533) are more abundant, and Echinoids (Figs. 531 and 

 532) are introduced for the first time. Fig. 534 represents the distri- 

 bution of these orders in time. 



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