ANCESTRY OP THE PEARLY NAUTILUS. 185 



The ocean Mab, the fairy of the sea 



Seems far less fragile, and alas ! more free. 



He when the lightning-winged tornadoes sweep 



The surge, is safe his port is in the deep 



And triumphs o'er armadas of mankind 



Which shake the world, yet crumble in the wind." 



It was the Paper Nautilus the Argmauta Argo which 

 from the time of Aristotle was believed to come to the surface 

 and " spread to the wafting breeze a two-fold sail." Even 

 this pretty fancy has been dispelled by truth-loving science. 

 The Paper Nautilus, when it wishes to travel, simply folds its 

 arms together, and from its funnel squirts a stream of water, 

 like the most common squid, and makes " head way" back 

 foremost. Our Pearly Nautilus is a relative of this; but he 

 too, is no sailor. He can indeed float with all his tentacles 

 outspread, but his normal place is on the bottom of the sea, 

 and his normal gait is a sprawling crawl on a set of flexible, 

 slippery tentacles, with mouth to the ground and back up. 



This Nautilus is the representative of a venerable dynasty. 

 The type is a survival from remote Palseozoic times. It per- 

 petuates a plan of structure so ancient that the bricks of As- 

 syria and the urns of buried Ilios are but memorials of yes- 

 terday. Its predecessors nay, perhaps truly, its ancestors 

 may be found lying in the tombs which every age of the 

 history of life and death has stocked with its memorials. The 

 Chambered Shell lies imbedded with its contemporaries in 

 strata of Carboniferous, Devonian, Silurian, and Cambrian 

 age. We have turned over their remains in searching for the 

 relics of those ages; but we have reserved to this time the 

 mention of this diversified type. But let us first glance at the 

 rocks which we are to explore. 



We shall call them Silurian. Very commonly they are 

 known as Upper Silurian. They lie many thousand feet down 

 from the surface, in regions where the series of strata is com- 

 plete. But, in other regions, they rise up to sunlight and 

 atmosphere, with all their treasures of the ancient world em- 

 bosomed in their solid mass. Here, also, is a great limestone 



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