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THE CHAMBERED NAUTILUS. 



In them, the shell is very delicate, and is rolled into a spiral form, something like 

 the proboscis of an elephant when curled up. These shells are very common on the 

 shores of New Zealand, where they are scattered in thousands, and are sometimes 

 thrown on the southern shores of England by the waves of the Gulf Stream. Yet the 

 animal which formed the shell is extremely rare, and is very seldom found except in a 

 very fragmentary and battered condition. 



ANOTHER order of cephalopods is called by the name of Tetrabranchiata, or Four- 

 gi'.led animals, because the organs of respiration are composed of four branchiae. 

 These creatures possess a very strong external shell, which is divided into a series of 

 gradually increasing compartments connected together by a central tube called the 

 siphuncle. As the animal grows, ft continues to enlarge its home, so that its age can 

 be inferred from the number of chambers comprising its shell. 



CHAMBERED NAUTILUS. Nautilus Pomptlius. 



In former times these creatures were very abundant, but in our day the only known 

 living representative is the CHAMBERED or PEARLY NAUTILUS, a section of which is 

 shown in the illustration in order to exhibit the beautiful spiral home in which the 

 creature resides, and the structure of the chambers, together with their connection by 

 means of the siphuncle. 



While the animal still lives, the short tubes that pass through the walls of the cham- 

 bers are connected by membranous pipes, and even in a specimen that has been long 

 dead, these connected links hold their places, provided that the shell has not been 

 subjected to severe shocks. In one of these shells now before me, which I have very 

 cautiously opened, the whole series of membranous tubes can be seen in their places, 

 black and shrivelled externally, but perfect tubes nevertheless. 



At the left-hand of the illustration the animal may be seen as it appears when lying 

 in its shell, the eye just peering from the edge, the points of the retracted tentacles 



