78 UNIVALVES. — NAUTILUS. 



NAUTILUS.— Pearly Sailor. 



Animalf — (vide Rumpf. Mus. tab. \7,fig. B.) Shell uni- 

 valve, divided into several compartments, communicating 

 with each other by an aperture. 



THIS genus contains thirty-six species, which are all 

 nearly allied in general formation and structure. The 

 most characteristic mark of the genus is, that the whirls 

 are generally divdded into distinct compartments or cham- 

 bers, connected by a slender siphon, which runs spirally 

 through the shell. This siphon 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 re- 

 semble the Dentalia. The whirls in the first division are 

 contiguous ; while, in the second and third, they are de- 

 tached. 



The N. pompilius, when bisected, exhibits in an eminent 

 degree the pearly concamerations for which this genus is 

 distinguished. The inhabitants of the East often convert 

 fine specimens of the above species into drinking cups; 

 they carve the surface into various devices and ornaments, 

 and also frequently remove the outer coating entirely, by 

 which the beautiful pearly appearance of the shell becomes 

 visible. The umbilicated varieties of this species are rare. 

 The size of the Nautili differs exceedingly ; some are so 

 small as only to be defined by the microscope. 



Some species of this genus are found adhering to coral 

 rocks; the N. siphunculus is often found on the coral reefs 

 on the Sicilian shores. 



The American and Indian oceans, and the Mediterra- 

 nean, Adriatic, and Red seas, produce some of the species 



