NOMENCLATURE. 31 



Stride. See above. 



abbreviate. Abbreviated ; not extending to the 

 margin. 



bifaria. Bifarious; diverging. 



recurvata. Recurved ; elevated, membranaceous ; 

 tending towards the apex. 



intequilineata, Inaequilinear; not parallel. 



Sulci. See above; sometimes they are used, 

 though perhaps improperly, to signify the 

 same as Costa, Ribs. 



forjiicati. Arched ; covered with arched scales. 



Testa. See above. 



antiquata. Antiquated ; longitudinally sulcate or 

 furrowed, but interrupted by transverse 

 accretions, as if lesser valves were periodi- 

 cally added to the apex or beak. 



aurita. Eared ; the hinge produced on either 

 side the beaks into a flat prominent 

 angle. 



barbata. Bearded ; superficially covered with 

 rigid hairs. 



compressa. Compressed; the valves flattened, 

 and the bosses less than usually gibbous. 



