452 DOMAIN V. CALCAREOUS. 



shells. To enumerate all the shells contained in lime- 

 stone would be infinite ; nor have such as occur 

 in rocks been hitherto carefully distinguished from 

 such as are found detached and scattered. It will 

 be sufficient for the present purpose to mention 

 such as are generally inherent in large masses of 

 limestone, konite, or marble ; thus forming, as it 

 were, a constituent part of these rocks. This 

 subject will be further illustrated by the plates. 



It has been observed as unaccountable, that 

 the shells of those fish which are called Pelasgic 

 or Oceanic, as inhabiting the unfathomable depths 

 of the ocean, are often found at the greatest ele- 

 vations ; while those which approach the less pro- 

 found depths, and even the shores, are rather 

 found on the skirts and lower hills. If this ob- 

 servation be exact, the explication seems very 

 difficult, except perhaps that, under the chaotic 

 waters, the proper purity and temperature to sup- 

 port animal life could only be found at such ele* 

 yations. 



The shell venerated as the most ancient, and 

 unknown in modern conchology, is that called 

 the Cornu Ammonis, or horn of Jupiter Ammon, 

 from the twisted horn, a symbol of power in the 

 images of that deity. In the middle ages they 

 were supposed to be petrified serpents, and some- 

 times fraud has cut out heads, being esteemed 





