22 CLASS MOLLUSCA. 



direct its course, and thus it pursues its voyage ; and, if 

 alarmed by any appearance of danger, takes in the water 

 and descends." 



Although the Argonaut has never yet been discovered 

 attached to its shell, some observations which have been 

 recently made on the Pearly Nautilus, which very nearly 

 esembles it, have almost proved that such a conn exion 

 does really exist. But whether the shell is formed by 

 itself, or only used to assist the creature in its move- 

 ments, the instinct displayed is not the less wonderful, 

 or worthy of observation. The Mediterranean, and 

 warmer parts of the Atlantic, abound in these interest- 

 ing animals, and one species is also found in the Indian 

 Ocean. 



The Pearly Nautilus, (Nmdihis jjompilins.) 



The inhabitant of this singular shell had long been 

 sought after with eagerness by naturalists, and it is 

 only within these few years that its true nature has been 

 ascertained. AVe are indebted for this knowledge to the 

 researches of the late Mr. George Bennet, who, while 

 engaged in a voyage among the Polynesian Islands, 

 captured a specimen containing a living animal, which 

 was brought to England, and is now deposited in the 

 I^Iuseum of the Royal College of Surgeons in London. 



The shell of the Nautilus, as may be seen by the 

 engraving, is divided into numerous cells. The use of 

 these cells to the animal we are now describing, was 

 formerly not well understood, but they were supposed to 

 be employed, by their inhabitant, for the purpose of rising 

 or sinking in the Water at will. The body of this Ce- 

 phalopod, it will be seen, only occupies the outer cell 

 ■of its habitation, its increased size having rendered it 



