70 UNIVALVES. NAUTILUS. 



NAUTILUS— Pearly Sailor. 



Animal — (vide Rumpf. Mus. tab. 17, fig-^O Shell uni- 

 valve, divided into several compartments^ communicating 

 with each other by an aperture. 



This genus contains thirty-one species, which are all 

 nearly allied in general formation and structure. The 

 most characteristic mark of the genus is, that the whirls 

 are generally divided into distinct compartments or cham- 

 bers, connected by a slender syphon, which runs spirally 

 through the shell. This syphon is in some species cen- 

 tral, and in others contiguous to the surface. 



The shells of the first and second divisions are spiral 

 or scroll-like; but, in the third, they are dentiform, and 

 resemble the dentalia. The whirls in the first division 

 are contiguous, while, in the second and third, they are 

 detached. 



The N.pompilius, when bisected, exhibits in an emi- 

 nent degree the pearly concamerations for which this ge- 

 nus is distinguished. The inhabitants of the East often 

 convert fine specimens of the above species into drinking 

 cups J they carve the surface into various devices and or- 

 naments, and also frequently remove the outer coating en- 

 tirely, by which the beautiful pearly appearance of the 

 shell becomes visible. The umbilicated varieties of this 

 species are exceedingly rare. 



The size of the Nautili differs exceedingly ; some are 

 so small as only to be defined by the microscope, while 

 others, especially some of the fossil species, exceed two feet 

 in diameter. 



