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 



Fig. 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 



