A1. Shape

General shape of the shell
 
 

Character State	Definition	Illustration
equivalve	Right and left valves subequal and comprising mirror images of one another except for hinge structures
inequivalve	Opposite valves dissimilar in size or shape or both
prosogyral	Beaks directed forward
opisthogyral	Beaks turned backward instead of projecting forward In this case, you use the fact that the beak is closer to the anterior rather than the fact that the beak points to the posterior of this shell. This is a picture of the left valve, not the right valve.
taxodont	Characterized by more or less numerous subequal hinge teeth, generally arranged in a row
mytiliform	Slipper-shaped
auriculate	Shell possessing auricles; equivalent to alate
produced	Shell much elongated in one direction
prosocline	Having forward obliquity, approach to beak along mid-line of shell inclined forward

 

Last updated on September 3, 2002-eek.