216 INTRODUCTION TO CONCHOLOGY. 



Each of these interesting genera might be regarded by 

 a casual observer merely as Limpets, but, when carefully 

 examined, they are found to possess characteristics that ex- 

 clusively belong to each. 



Little is known with certainty as regards their peculiar 

 liabits, and the Conchologist, when looking at them, can 

 only regret the impossibility of becoming acquainted with 

 all their instincts and detailed peculiarities. They dwell, 

 it may be, among those groves of gigantic algae, whose tall 

 yet sessile stems rise to a great height and partly float on 

 the surface of the water by means of innumerable air- 

 vessels, which give them buoyancy ; or, perchance, in coral 

 caves, where phosphorescent insects shine like tiny lamps 

 among the fissures, and light the creatures of whom we 

 speak, in their perambulations from place to place. Nor 

 is this the fond imagining of poetic fancy, nor yet the 

 reverie of one who delights in fairy legends ; the luminous 

 appearance of the sea has long since been ascertained to 

 result from such minute insects, that one of them would 

 require to be magnified at least fom- hundred times before 

 attaining the dimensions of a grain of sand. 



"Who shall assign a limit to the wonders of creation ! 

 Living lamps diffuse their cheering rays in solitary caverns. 



