PLICA CEA. 151 



genus, by wanting the notch at the base which indicates the 

 passage of an uplifted fold of the mantle used for the con- 

 veyance of water to the breathing organs; and from the 

 last by an oceanic location — a fact assumed from the hard 

 porcelain structure of the shell, which seems to indicate that 

 the constructors are of marine habits, denizens neither of 

 fresh water nor of land. They have, moreover, a horny 

 operculum, which serves to protect them in their watery 

 location. 



Two genera, the Fyramidella and Tornatella, both very 

 limited in species, are alone referred to this family. 



Assuming that every creature is wonderfully constructed, 

 and adapted to its sphere of being, whether pertaining to 

 the elements of earth, or air, or water, the two preceding 

 genera have, without doubt, an especial reference to their 

 individual localities ; the peculiarities of such locations must, 

 however, remain unknown. We know little concerning 

 the bed of ocean, as regards its geographic character, 

 although sufficient has been discovered to prove that it is 

 equally varied with the land ; — that huge marine rocks lift 

 their summits to the air and Hglit ; — that plains extend in 

 all directions ; — and deep sloping valleys, with caves, and 

 giant sea-weeds, exliibit an infinite variety of oceanic vege- 

 tation. 



