ID Keys

Crassatelloidea

#1
Sculpture of acentric grooves decreasing in spacing towards the margins
Digitaria digitaria
  
Sculpture smooth or commarginal lines or ridges
Go to #2
  
#2
Back to #1
Back to start
Rounded triangular, commonly taller than long
Go to #3
  
Subtrigonal or subovate to slightly triangular
Go to #4
  
#3
Back to #2
Back to start
Very fine commarginal lines and irregular growth stops, found to 200m
Goodallia triangularis
  
Broad commarginal ridges, found intertidal and to 200m
Astarte montagui
  
#4
Back to #2
Back to start
Subovate, thick, dark periostracum covering commarginal lines and irregularly spaced low ridges, Arctic/subarctic
Astarte borealis
  
Rounded subtrigonal/triangular, regular spaced commarginal ridges
Go to #5
  
#5
Back to #4
Back to start
Subtrigonal, dense commarginal, narrow ridges that are acute on the posterior area, bathyal
Astarte acuticostata
  
Oval to subtrigonal, commarginal ridges rounded
Go to #6
  
#6
Back to #5
Back to start
Broadly rounded oval outline, raised commarginal ridges, magnified periostracum a mesh of microscopic elliptical-oval pits
Astarte elliptica
  
Subtrigonal
Go to #7
  
#7
Back to #4
Back to start
Ridges smooth, widely spaced, magnified periostracum fine wavy linear pattern, widely distributed throughout study area
Astarte sulcata
  
Ridges closely spaced with secondary commarginal lines especially over the posterior area, magnified periostracum lacking wavy linear pattern, boreal arctic species
Go to #8
  
#8
Back to #5
Back to start
Magnified periostracum commarginally wrinkled but not punctate, lustrous
Astarte crenata
  
Magnified periostracum commarginally wrinkled and micro-punctate
Astarte crebricostata