SPIRULAS, NAUTILI, AND AMMONITES. 



195 



long, and, like cuttle-fishes, have ten arms, two of -which 

 are longer than the others. By filling their body with 



Kg. 361. — Ammonite. 



Fig. 362. — Spirula. 



Fig. 363. — Pearly Nautilus. Much reduced. 

 Pacific and Indian Oceans. 



water, and then forcibly ejecting it, they send them- 

 selves backwards through the water with the swiftness 



