482 



MESOZOIC ERA— AGE OF REPTILES. 



Fig. 801. 



802. 



Figs. 797-803. — Cretaceous Cephalopods : 797. Ammonites Chicoensis (after Gabb). 798. Scaphi- 

 tes sequalis (after Pictet). 799. Crioceras, restored (after Pictet). 800. Helioceras Robertianus 

 (after Pictet). 801. Ancyloceras percostatus. x | (after Gabb), 802. Baculites anceps, x J (after 

 Woodward). 803. TurruJites catenatus (after D'Orbigny). 



Vertebrates — Fishes. — In the development of this class some de- 

 cided steps in advance are here recorded. Placoids and Ganoids still 

 continue, but Teleosts, or true typical modern fishes, are here intro- 

 duced for the first time, and in considerable numbers, and some of 

 gigantic size, These earliest Teleosts were related to salmon, herring, 

 perch, pike, etc. Beryx, a genus still found in open seas, is found in 

 the Chalk of Europe and Upper Cretaceous of America. Among Pla- 

 coids, too, although the Cestracionts and Hybodonts continue (the lat- 

 ter, however, passing out with the Cretaceous), the modern type, the 

 true sharks or Squalodonts, having lancet-shaped teeth, are for the 

 first time abundant. We give figures of Cestraciont and Squalodont 



