BIVALVES. MYA. 37 



MYA Gaper. 



DIVISION I. Hinge with one or two rounded teeth, not inserted 

 in the opposite valve. 



Glycymeris Great. Rostrata Beaked. 



*Truncata Abrupt. *Distorta Deformed. 



* Arenaria Sand. *Bidentata Double- toothed. 

 *Declivis Sloping. *Decussata Decussated. 

 *Pubescens Pubescent. *Purpurea Purple. 

 *Preetensus Spoon-hinge. *Ferruginosa Rusty. 

 Anatina Duck. . Nitens Glossy. 



Globosa Globular. *Prismatica Prismatic. 



Nicobarica Nicobar. *Substriata Substriated. 



DIVISION II. Hinge callous, without teeth. 



E dentula Toothless. Norwegica Norwegian. 



Membranacea Membraneous. Siliqua Bean-pod. 



DIVISION III. Hinge with teeth inserted into the opposite valve. 



* Batava Dutch. Corrugata Wrinkled. 

 *Pictorum Painters'. Rugosa Rough. 

 *Ovata Oval. Variabilis Variable. 

 Radiata Radiated. Nodosa Knobbed. 

 Ponderosa Ponderous. Syrmatophora Angular. 

 Complanata Smooth. *Suborbicularis Roundish. 

 Nodulosa Knotted. *Inaequivalvis Inequivalve. 

 *Margaritifera Pearl. Labiata Lipped. 



Aurita Eared. 



DIVISION IV. Hinge toothless, with a conical rounded hollow for 

 the reception of the cartilage. 



Vulsella Tweezers. 



