304 GASTEROPODES. 



week subsequent to the preceding remarks, it broke up when depositing, 

 thus giving exit to a multitude of Nautilines, which swam with great 

 activity ; various individuals pursuing their course singly through the 

 water, or several clustering together, were seen in horizontal revolution 

 in the same place. Sometimes two in contact performed a common revo- 

 lution, while many solitary animals did the same. It was a most peculiar, 

 amusing, and interesting spectacle. Fig. 15. But nothing more than 

 what has been already recorded distinguished these diminutive beings. 

 Sometimes, indeed, as may be readily imagined, a better view of species 

 or of individuals may be obtained than usual. But we can scarcely allow 

 that it is ever satisfactory : it may be often illusive ; and, while instruct- 

 ing others, we may be unwittingly misled by imperfect observation. It 

 seems to have been no part of the design of the Creator that the Nautiline 

 should meet the eye of mankind. In fact, although we strive to render 

 it plain, it is always seen imperfectly. Mere enlargement on a flat sur- 

 face is not all that is required. 



The parts of so minute an animal, passing through metamorphoses, 

 are obscurely visible perhaps ; but their functions may be the subject of 

 conjecture. Observations, however, are generally intercepted, first by 

 the water, however pure, secondly by the shell, however transparent. 

 Thus they can never be entirely exposed, or always under the same aspect, 

 to say nothing of the fallacies generally concomitant on microscopical ob- 

 servation. 



Like its fellows, the Nautiline of the Eolis occupies a shell, serving 

 as a receptacle whither it can retreat completely. It can return to dis- 

 play itself at pleasure, protruding partially beyond the orifice. There is 

 the appearance of two cylinders, with marginal cilia in rapid motion, pre- 

 cisely as exhibited by the revolution of a wheel. When thus relaxed, the 

 motion became so slow, that each of the cilia seemed to be distinguished 

 distinctly. The two black points, previously alluded to, remained always 

 apart, below the cylinders. Fig. 16. 



Some features inexplicable were presented by these minute creatures. 

 At certain times preceding the protrusion of the body from the shell, a 

 lid seemed to fold back, as if by a hinge. My artist, occupied in delinea- 



