364 The Life of the Spider 



the oceanic ooze. Cut and polished length- 

 wise, the fossil shows a magnificent logarithmic 

 spiral, the general pattern of the dwelling which 

 was a pearl palace, with numerous chambers 

 traversed by a siphuncular corridor. 



To this day, the last representative of the 

 Cephalopoda with partitioned shells, the Nautilus 

 of the Southern Seas, remains faithful to the 

 ancient design ; it has not improved upon its dis- 

 tant predecessors. It has altered the position of 

 the siphuncle, has placed it in the centre instead 

 of leaving it on the back, but it still whirls its 

 spiral logarithmically as did the Ammonites in 

 the earliest ages of the world's existence. 



And let us not run away with the idea that 

 these princes of the Mollusc tribe have a mono- 

 poly of the scientific curve. In the stagnant 

 waters of our grassy ditches, the flat shells, the 

 humble Planorbes, sometimes no bigger than 

 a duckweed, vie with the Ammonite and the 

 Nautilus in matters of higher geometry. At 

 least one of them, Planorhis vortex, for example, 

 is a marvel of logarithmic whorls. 



In the long-shaped shells, the structure 

 becomes more complex, though remaining 



