VERTEBRATA. 309 



can be protruded or retracted at pleasure, and the 

 mouth is surrounded with a series of tentacles still 

 more numerous. The Nautilus is, moreover, unpro- 

 vided with an ink-bag ; its beak is thick, and of 

 stony hardness, apparently adapted to crush shells or 

 corals, which most probably constitute its ordinary 

 food. 



The Nautili are not found in any great depth of 

 water, but principally inhabit the reefs near which 

 their food is most abundant. They creep about these 

 reefs, with their shell uppermost, like a snail, and 

 devour crabs and other crustaceans that come in 

 their way, or they return and remain in a chasm of 

 the rock, with their numerous tentacles spread out 

 in all directions, waiting for prey to approach near 

 enough to be captured. The feelers are very 

 numerous, and evidently endowed with a keen sense 

 of touch, but are quite destitute of the sucking disks 

 so remarkable in the Cuttle-fish. When at the 

 surface of the water, the Nautilus Pompilius drifts 

 with the current or breeze ; its navigation is passive, 

 or at most influenced by the jets of water expelled 

 occasionally through the funnel. The natives of the 

 New Hebrides, New Caledonia, and the Fidgi groups 

 of islands capture it and use it as an article of food. 

 When the water is smooth, so that the bottom at 

 several fathoms of depth can be distinctly seen, the fish- 

 erman in his canoe scrutinizes the sands and the coral 

 rocks to discover the animal in its favourite haunts. 



CHAPTER XXI. 



VERTEBRATA. 



THE fifth division of the Animal Creation is com- 

 posed of four great classes, closely allied to each 

 other in the grand features of their organization, and 

 possessing in common a general type of structure, 

 clearly recognizable in every member of the ex- 



