42 NOMENCLATURE. 



aunjormes. Auriform; ear-shaped, having an 

 incurvated arch between the beaks. 



corniformes. Corniform ; horn-shaped, long, pro- 

 duced, straight, mucronate, or pointed. 



inficxi. Inflex -, incurved, bending towards each 

 other. 



reJl^xL Reflex; turned towards the areola. 



spirales. Spiral ; twisted spirally. 



Auricula. Ears ; angular processes either on 

 one or on both sides of the beaks. 



Basis. Base ; that part of the margin which is 

 immediately opposite to the beaks or sum- 

 mit. 



Cavitas. Cavity; hiterior superficies of the 

 shell. 



Callus. Callus ; composed as it were of two 

 abbreviated ribs, united at the base, con- 

 verging from the apex towards the poste- 

 rior style. 



Cardo. Hinge; that part of the circumference 

 in which the valves cohere, or are attached 

 to each other. It constitutes the thickest 

 region of the shell, and is inwardly fur- 



