472 



THE OCEAN WORLD. 



of a heart, with a ventricle and auricle. The shell is secreted by the 

 outer edge of the mantle, while its posterior extremity fashions the 

 walls of the partitions, which indicate the successive growth of the 

 individual. 



Fig. 321 represents the shell of Nautilus, with the animal re- 

 moved ; the last partition is seen empty, and with the perforations 

 through which the siphuncle passes. 



The genus Nautilus inhabits the Indian Ocean and the sea round 

 the Molucca Islands. In swimming, the head and tentacles are 

 projected from out of the shell. In walking on rocks, they drag 

 themselves along the ground, the body upwards, the head and 



Fig. 321. — Nautilus pompilius (Linnxus), 

 showing the lower cell and the partition giving passage to the siphon. 



tentacles beneath. They betake themselves frequently to miry 

 cavities frequented by fish. It is a much more common occurrence 

 to find the empty than inhabited shells of the Nautilus at sea. 

 This probably arises from its exposure to the attacks of crustaceans 

 and other marine animals, which seems to be proved by the mangled 

 appearance of the edges of the empty shells thus met with. 



The Pearly 'i^SMtWns, Nautilus pompilius (Fig. 322), is said to be 

 so common on the Nicobar coast that the inhabitants salt and dry 

 its flesh, and store it as provisions. Its shell attains about eight 

 inches in its greatest height. This shell is said to be still used by the 

 Hindoo priests as the conch with which they summon their devotees 

 to worship. It is nearly round, smooth, transversely blazed in its 

 posterior part, and entirely white anteriorly. A very fine nacre is 

 yielded by this mollusc, which is much used in ornamental cabinet- 

 work. The Orientals make drinking-cups, on which they engrave 



