EVENINGS AT THE MICROSCOPE 



These little organs are eyes. As its movements are far 

 more extensive, and more fitful and rapid than is common 

 in this class of animals, the little Pecten probably needs 

 these brilliant organs of vision to guide its wayward rov- 

 ings, 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 cau- 

 tion, 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 chil- 

 dren often make with a narrow ribbon round the edges of 

 these very Scallop-shells, you can hardly 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 the two rows 

 of diamond-headed pins, carefully and regularly stuck 

 along the two edges of the pin-cushion ribbon the rib- 

 bon itself representing 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 dia- 

 monds. 



You will not fail to remark how the position of these 

 beauteous organs is suited for their most extensive useful- 

 ness consistent with their safety. In the ordinary condi- 

 tion of the animal's expansion, and especially when it is 



