IN DESCRIBING SHELLS. 27 



a long square with the corners rounded oil", as Tellina 



7^adiata. 

 Triangitlatus, triangular, as Mactra suhtruncata. 

 Cordatus, heart-shaped, but compressed thin, as Cardium Car- 



dissa. 

 Lingucefonnis, tong-ue-shaped, long, and rather tapering, as 



Mya Vulsella. 

 Ctoieiformis, wedge-shaped, as Donax cuneata. 

 Auricidatiis is with two small appendages or wings, called by 



Linnseus ears, as in Ostrea maxima, the common Scallop 



ipl. 4. /. 41). 



OF THE PARTS OF BIVALVE SHELLS. 



First, of the Beaks. 

 Nates or Umbo, a beak, is a blunt point which may be seen 



on the outside of each valve near the hinge. 

 Incurvatus or Injiexus is when the beaks are curved inward, 



as in Area Glijci/meris. 

 Reciirvatus or Hejiexm is when the beaks are curved back- 

 ward, as in Chama Cor. 

 Approximatus is when the two beaks are near together, or 



stand approaching to each other, as Cardium Cardissa. 

 Distans is when the two beaks stand at a distance from each 



other, as in Cardium Hemicardium. 

 Remotissimus is when tliey stand at a greater distance from 



each other, as in Area Noce. 

 Prorninulus is when the beaks are but little prominent, or 



E 2 



