THE AMMONITES 



In the Jurassic strata and in the Greensand 

 and Chalk wonderful coiled shells are very 



Fig. 193. — Ammonites {Aegoceras capricornus) from the Lower 

 Lias of England. 



commonly found which have been compared 

 by the country-folk to petrified snakes and to 



Fig. 193a. — The shell of the Pearly Nautilus, cut in half so as 

 to show the air chambers in the coils of the shell. (Lent 

 by the Trustees of the British Museum. ) 



the coiled horns of the ram. These are the so- 

 called Ammonites (Fig. 193), of which there 



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