26 TERMS USED 



straight, the margins of the valves being parallel to each 



other, as Soleti Vagina and Siliqua. 

 Linearis-snharcnatus is long and a little bent, with the margins 



parallel, as Solen Ensis. 

 Navicidaris is boat-shaped, as Area Note. 

 Semi-orbicidatus is shaped like half a globe, as Chama orbiculata. 

 Cordatus is when the valves together nearly form the shape of 



a heart, as Cardium Isocardia. 

 Triangidus-cordatus is between triangular and heart-shaped, 



as Donax Scoi^tum. 

 Triangulus-rotundatus is between triangular and rovuid, as 



Venus castrensis. 

 Sub-rhomboideus is somewhat like a rhomboid, as Ai^ca lactea. 

 Trapezius is irregularly four-sided, as Chama trapezia. 



(Sidj being prefixed to any term, means rather, or a little. 

 Ob, when prefixed to any term, means about.^ 



OF COMPRESSED FORMS. 



Orbiculatus is round and flat, as Anomia Placenta. 

 Sub-rotundus is somewhat round and flattis]i,as MactraListeri. 

 Lentiforniis is round like a lentil, slightly convex on eacli 



side, with a sharp edge, as Venus tigerina. 

 Ovatus, egg-shaped, is broader at one end than the other, as 



Tellina planata. 

 Ovalis, oval, differs from ovatus in having the two ends equal, 



or nearly so, as Tellina Gari. 

 Oblongus is longer in proportion to tlie breadth, and more like 



