CEPHALOPODS. 



471 



shore, in our narrow channel, the charming picture of the Nautilus 

 painted by poets and natural historians : they never come near the 

 shore. They are timid and cautious creatures, dwelling almost always 

 in the open sea. They live in families, some hundreds of miles from 

 the shore ; and it is during the night, or at most in the fading light 

 of sunset, that they assemble together to pursue their gambols on the 

 surface of a tranquil sea. 



However reluctant we may be to destroy the marvellous fictions of 

 ancients and moderns, we are compelled to declare that there is no 

 truth in the often-repeated statement that the Nautilus uses its pal- 

 mated arms as oars or sails. In order to swim on the surface, it 



Fig. 329. Argonauta papyracea, as it swims by means of its locomotive tube. 



comports itself as all other Cephalopods do. It uses neither oars nor 

 sails, and the palmate arms only serve to envelop and retain its hold 

 on its frail shell. Its principal apparatus of progression is the 

 locomotive tube with which it is furnished, in common with all Cepha- 

 lopods, and which is in the Nautilus very long. Aided by this 

 apparatus, it ejects the water after it has served the purpose of 

 respiration, and, in doing so, projects itself against the liquid, as it 

 were. While it advances through the water under this impulse, its 

 pendent arms, elongated and reunited in bundles, extend the whole 

 length of the shell. Fig. 329 shows the 

 position of the different parts of the 

 animal when it thus breasts the waves. 

 These arms are also powerful aids when 

 the animal creeps on the ground at the 

 bottom of the sea. 



When the animal is disturbed it re- 

 tires Completely into its Shell. From Fig> 330< Argonauta papyracea in its 



that moment, the equilibrium being 



changed, the shell is overturned, and the animal is nearly invisible. 



If frightened, it entirely submerges itself, and sinks to the bottom. 



