Archerd Shell Collection > Shell Classes > Bivalvia > Mactridae

Family: Mactridae (Surf or Trough Clams, Mactras)

Surf clams like to burrow in rocks, and the shell is consequently quite strongly constructed.  The shell surface is smooth, with concentric growth lines, and covered with a thin periostracum. The resilium (part of the hinge ligament inside the edges of the valves) is large and situated in a chondrophore, the spoon-shaped pit on the interior of the bivalve shell that contains the internal ligament. Lateral teeth are usually present, and the cardinal teetah are weekened. The mantle line has a posterior sinus.
The shell shown opposite, Mactrellona exoleta, is actually rather similar to Mactrellona clisia. However, a sharp angulation on the left (posterior) end, and the absence of a "keel" at the edge where the shell is flattened identifies it as M. exoleta (Keen).
Class: Bivalvia
Subclass: Heterodonta
Order: Veneroida
Superfamily: Mactracea
Family: Mactridae
Major Genera
  • Genus: Anatina
  • Genus: Lutraria
  • Genus: Mactra
  • Genus: Mactrellona
  • Genus: Raeta
  • Genus: Rangia
  • Genus: Spisula
  • Genus: Tresus
Mactrellona_exoleta.JPG (41853 bytes)

Mactrellona_exoleta2.JPG (41386 bytes)Mactrellona exoleta (Gray, 1837)
Ripe Mactra


Tresus capax
Horse Clam

Archerd Shell Collection > Shell Classes > Bivalves > Surf, Trough, or Mactra Clams