THE '-'SAILING'' OF THE NAUTILUS. 87 



at rest to dangle over the side of the " boat ; " but are used 

 as a kind of hood by which the animal retains the shell in 

 its proper position, as a man bearing a load on his shoulders 

 holds it with his hands. When she comes to the surface, 

 or progresses by swimming instead of walking, she does so 

 in the same manner as the octopus: namely, by the forcible 

 expulsion of water from her funnel-like tube. 



But if truth compels us to deprive her of the counterfeit 

 halo conferred on her by poets, we can award her, on behalf 

 of science, a far nobler crown ; namely, that of the Queen 

 of the whole great Invertebrate Animal Kingdom. For, 

 the Cephalopoda, of which the argonaut is a highly 



FIG. 30. — THE PAPER NAUTILUS {ArgOfiauta argo) SWIMMING. 



organised member, are not only the highest in their own 

 division, the Mollusca, but they are as far superior to all 

 other animals which have no backbones, as man stands 

 lord and king over all created beings that possess them. 



Although in outward shape the spiral shell of the Pearly 

 Nautilus {Nautilus poiupiliiis) somewhat resembles that of 

 the argonaut, its internal structure is very different. A 

 section of it shows that it is divided into several chambers, 

 each of which is partitioned off from the adjoining ones, the 

 last formed or external one, in which the animal lives, being 

 much larger than the rest. The object and mode of 

 construction of these chambers is as follows. As the 

 animal grows, a constant secretion of new material takes 

 place on the edge of the shell. By this unceasing process 



