136 UNIVALVES. 



degree. Around Paris these shells are found in 

 the fossil state in such prodigious quantities, that 

 small as they are, they form the principal part of 

 the immense masses of stone which constitute 

 some of the quarries. 



NAUTILUS Pompilius* 

 LARGE CHAMBERED NAUTILUS. 



Specific character. Shell with an involuted 

 and concealed spire, smooth ; aperture cordate ; 

 colour whitish, with waved streaks of reddish or 

 yellowish brown, pearly within. 



This beautiful shell is often converted by the 

 inhabitants of the East into a drinking cup ; on 

 the surface they engrave various ornaments and 

 devices. 



NAUTILUS Spirula. 

 CROSIER NAUTILUS. 



Specific character. Shell thin, brittle, trans- 

 parent, with five cylindrical detached whorls 

 divided into numerous compartments ; distin- 

 guished on the outside by a depressed circular 

 line ; the last volution takes a straight direction, 

 and is remote from the adjoining one ; aperture 

 orbicular, pearly within ; chambers separated by 

 their pearly plates, but communicating with each 



* Plate VI. figure 4. 



