The Collaborative International Dictionary of English v.0.48:

Sea clam \Sea" clam`\ (Zool.)
   Any one of the large bivalve mollusks found on the open
   seacoast, especially those of the family Mactridae, as the
   common American species. (Mactra solidissima or Spisula
   solidissima); -- called also beach clam, and surf clam.
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The Collaborative International Dictionary of English v.0.48:

Surf \Surf\, n. [Formerly spelled suffe, and probably the same
   word as E. sough.]
   The swell of the sea which breaks upon the shore, esp. upon a
   sloping beach.
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   Surf bird (Zool.), a ploverlike bird of the genus
      Aphriza, allied to the turnstone.

   Surf clam (Zool.), a large clam living on the open coast,
      especially Mactra solidissima (syn. Spisula
      solidissima). See Mactra.

   Surf duck (Zool.), any one of several species of sea ducks
      of the genus Oidemia, especially Oidemia
      percpicillata; -- called also surf scoter. See the Note
      under Scoter.

   Surf fish (Zool.), any one of numerous species of
      California embiotocoid fishes. See Embiotocoid.

   Surf smelt. (Zool.) See Smelt.

   Surf whiting. (Zool.) See under Whiting.
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The Collaborative International Dictionary of English v.0.48:

Clam \Clam\ (kl[a^]m), n. [Cf. Clamp, Clam, v. t.,
   Clammy.]
   1. (Zool.) A bivalve mollusk of many kinds, especially those
      that are edible; as, the long clam (Mya arenaria), the
      quahog or round clam (Venus mercenaria), the sea clam or
      hen clam (Spisula solidissima), and other species of the
      United States. The name is said to have been given
      originally to the Tridacna gigas, a huge East Indian
      bivalve.
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            You shall scarce find any bay or shallow shore, or
            cove of sand, where you may not take many clampes,
            or lobsters, or both, at your pleasure. --Capt. John
                                                  Smith (1616).
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            Clams, or clamps, is a shellfish not much unlike a
            cockle; it lieth under the sand.      --Wood (1634).
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   2. (Ship Carp.) Strong pinchers or forceps.
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   3. pl. (Mech.) A kind of vise, usually of wood.
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   Blood clam. See under Blood.
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