The Life of the Spider 



ful to the ancient design; it has not improved 

 upon its distant 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 

 monopoly 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 Ammo- 

 nite and the Nautilus in matters of higher 

 geometry. At least one of them, Planorbis 

 vortex, for example, is a marvel of logarith- 

 mic whorls. 



In the long-shaped shells, the structure 

 becomes more complex, though remaining 

 subject to the same fundamental laws. I have 

 before my eyes some species of the genus 

 Terebra, from New Caledonia. They are ex- 

 tremely tapering cones, attaining almost nine 

 inches in length. Their surface is smooth and 

 quite plain, without any of the usual orna- 

 ments, such as furrows, knots or strings of 

 pearls. The spiral edifice is superb, graced 



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