98 Beautiful Shells. 



be so perfect and admirable, that eighty pounds 

 was afterwards offered for it, and refused. 



These Naidce have not a bissus like the Marine 

 Mussels, they are therefore never attached to one 

 object ; they use their foot as a propeller in tra- 

 versing the muddy floor of the pond or river, and 

 they have a very funny way of getting along indeed ; 

 first, they open the valves of the shell, put out the 

 foot, and, after some little hard work, manage to 

 set themselves up on edge ; they then proceed by a 

 series of jerks, leaving a deepish furrow in the mud 

 behind them. 



We will now go to Fig. 3, the Spined Cytherea, 

 the Cytherea, or Venus Dione of naturalists ; the 

 meaning of the term is the mother of Venus, who 

 was, as you will remember, the goddess of beauty, 

 given to this shell, perhaps, because it is entitled to 

 occupy a place at the head of the Cytherea, a genus 

 of the Cardiidce, or Cockle family, of which genus 

 there are about seventy-eight living species ; this, 

 as it is the most rare, is also, perhaps, the most 

 beautiful ; it is found in the seas of America, and is 

 remarkable for the row of spines on the hinder 

 border of each valve ; these vary much in size and 

 number, being in some individuals long and far 

 apart, in others, short, thick, and closely set. The 



