328 INTRODUCTION TO CONCHOLOGY. 



urchins, witli different kinds of shells, have been discovered, 

 some nestling among the branches, others pasturing on 

 the leaves, all instinct with life, and apparently susceptible 

 of enjo3^ment. Even the sand which adheres to the roots, 

 shelters many creatures of strange forms and instincts, — per- 

 fect in all their parts, extremely beautiful, yet so minute, 

 as to require a high magnifier in order to perceive them. 



Family X. Cahdiacea. 



It is pleasant to see how the billows run. 

 How tliey sparkle and flash to the rising sun, 

 Eeilecting the clouds in their aiiy ride, 

 And bearing along, as with conscious pride. 

 Sea-weeds and shells from the wild sea waves. 

 Which lie hid in the depth of the fathomless caves, 

 "Where the foot treadeth not, nor the eye may scan, 

 Deep, deep, from the haunts and the homes of man. 



The shell of the family Cardiacea is equivalve, cordi- 

 form or transverse, sometimes a little gaping; and the 

 valves are mostly characterized by being disposed in longi- 

 tudinal ribs diverging in symmetrical order from the um- 

 boes to the margin. There are generally two cardinal 

 teeth, irregular both in form and situation, and one or two 



