52 EVENINGS AT THE MICBO SCOPE. 



rovings, as well as to guard it from hostile assaults. The 

 animal is very sensitive, withdrawing its tentacles and 

 mantle, and bringing the valves of its shell together, on 

 any shock being given to the vessel in which it resides. It 

 manifests, however, a wisely measured degree of caution, 

 for it does not actually close the valves, unless it be 

 repeatedly disturbed, or unless the shock be violent, con- 

 tenting itself with narrowing the opening to the smallest 

 space appreciable ; yet even then the two rows of gem-like 

 eyes are distinctly visible, peeping out from the almost 

 closed shell, the two appearing like one undulating row 

 from the closeness of their proximity. 



If you are familiar with the pin -cushions which children 

 often make with a narrow ribbon round the edges of these 

 very Scallop-shells, you can scarcely fail to be struck with 

 the resemblance borne by the living animal to its homely 

 but useful substitute ; and the beautiful eyes themselves 

 might be readily mistaken for two rows of diamond- 

 headed pins, carefully and regularly stuck along the two 

 edges of the pin-cushion ribbon, the ribbon itself repre- 

 senting the satiny and painted mantle. A friend of mine, 

 to whom I was once showing this object, compared it, not 

 inaptly, to a lady's ring set with diamonds. 



You will not fail to remark how the position of these 

 beauteous organs is suited for their most extensive 

 usefulness consistent with . their safety. In the ordinary 

 condition of the animal's expansion, and especially when 

 it is about to make its sudden and vigorous leaps, the gem- 

 like points are so situated as just to project beyond the 

 margin of the shell. So that when we view the creature 

 perpendicularly as it lies, our eyes looking down on the 

 convexity of the upper valve, the minute eyes are seen, all 

 round its circumference, just, and but just, peeping from 

 under its edge. It is clear that this arrangement secures 

 to them the widest range of vision with the least possible 

 exposure. As Divine contrivance has been often most 



