204 FLOATING SHELLS. 



Sir Walter Scott alludes to this popular superstition in his^ 

 poem of *' Marmion,^ where the nuns of Whitby exultingly 



told 



" How of thousand snakes, each one 

 Was changed into a coil of stone 

 When holy Hilda pray'd." 



The visitors to Whitby are still invited to buy a pet- 

 rified snake, and to add to their natural appearance, the 

 mouth ,of the ammonite is carved into a head, and eyes are 

 introduced made of colored glass. 



The ammonite,with a shell a yard across,would have been 

 an animal large in proportion to its body-chamber, and 

 requiring a certain amount of water to be displaced by its 

 shell, to move at ease along the bottom of the sea in search 

 of its food. The shell of the ammonite,though of the same flat 

 character as that of the nautilus, appears to have been much 

 thinner ; but, to compensate for this, there were flu tings 

 which are seen in the surface, occasioned by the transverse 

 ribs. The round knobs or bosses studding some of the am- 

 monites were like gems on a diadem, adding strength as 

 well as beauty to their form. The whorls or wreaths of the 

 shell were rounder and more in number than that of the 

 nautilus, and the tubes — the hydraulic instinct by which the 

 chambers were supplied with air, or exhausted, for the as- 

 cent or descent of the animal — instead of running through 

 the cells like that of the nautilus, went round the chambers 

 of the ammonite. 



How strange are the vicissitudes of all created things I 

 While some survive the shocks and rents of time, others are 

 known only as fossil memorials of the primitive world. The- 

 nautilus still rides on the crest of the ocean waves, but the 

 ammonite — long, long since removed from the element in 

 which it lived — only remains as a petrifaction to tell of its 

 existence in ages before the Flood. 



We also mention the little floating Pterojpoda or Wine- 



