166 LECTURE XI. 



been supposed by some, that the animal pos- 

 sesses the power of at pleasure filling up the 

 chambers or cavities either with air or water, or 

 of exhausting them of both occasionally ^ in or- 

 der to make itself specifically heavier or lighter, 

 during its navigations; for this animal is also sup- 

 posed to have a power of sailing, though in a less 

 perfect manner than the Argonaut or Paper Nau- 

 tilus. The animal is also indistinctly allied to the 

 Cuttle-Fish tribe ; having an oval body, with the 

 front or central part furnished with a parrot-shaped 

 beak, and surrounded by arms or tentacula ; but 

 they differ from those of the Sepias or Cuttles 

 in being very short, extremely numerous, disposed 

 in several concentric rows or circles, and not be- 

 set with any visible suckers. From above the neck 

 or round the upper part of the head rises a large, 

 concave flap or hood, beset on the inside with nu- 

 merous but small suckers or concave tubercles. 

 By the elevation and expansion of this concave flap 

 or hood the animal of the Pearly Nautilus is sup- 

 posed to sail. It is of a pale reddish-purple co- 

 lour, with deeper spots and variegations. 



It is remarkable that this animal has also been 

 described and figured in the works of Rumphius, 

 but the drawing representing it in its recent and 



