   |
Nuculana concentrica
Nuculana concentrica (Say, 1824) - Concentric lined nut or Concentric nut clam
Measuring up to nearly 2 cm long, the Nuculana concentrica is strong, having an inequilateral roundly pointed anterior that tapers posteriorly to a fairly sharp point that turns slightly upwards. It is glossy white, cream, grey-white or grey in color. The interior of shell is usually the same color as the rest of the shell. It is sculptured by very fine and numerous concentric striae, but is nevertheless still quite smooth. The umbones are completely smooth and do not possess this sculpturing. The ligament internal and housed in a chondrophore, and it has 16-20 teeth in both anterior and posterior groups; the teeth are roughly equal in number in both the anterior and posterior groups. The pallial sinus is not easy to see. It is easily distinguished from Adrana scaphoides, A. egregia and A. gloriosa by its small size and from Y. crosbyana by its pointed posterior end. It was once uncommon. Double valves were found. |