Calcar

Hippocampus \Hip`po*cam"pus\, n. [L., the sea horse, Gr. ? a
   hippocampus (in senses 1 and 2); "i`ppos horse + ? to bend.]
   1. (Class. Myth.) A fabulous monster, with the head and fore
      quarters of a horse joined to the tail of a dolphin or
      other fish ({Hippocampus brevirostris}), -- seen in
      Pompeian paintings, attached to the chariot of Neptune.
      --Fairholt.
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   2. (Zool.) A genus of lophobranch fishes of several species
      in which the head and neck have some resemblance to those
      of a horse; -- called also {sea horse}.
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   Note: They swim slowly, in an erect position, and often cling
         to seaweeds by means of the incurved prehensile tail.
         The male has a ventral pouch, in which it carries the
         eggs till hatched.
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   3. (Zool.) A name applied to either of two ridges of white
      matter in each lateral ventricle of the brain. The larger
      is called hippocampus major or simply hippocampus. The
      smaller, hippocampus minor, is called also {ergot} and
      {calcar}.
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Calcar \Cal"car\, n. [L. calcaria lime kiln, fr. calx, calcis,
   lime. See {Calx}.] (Glass manuf.)
   A kind of oven, or reverberatory furnace, used for the
   calcination of sand and potash, and converting them into
   frit. --Ure.
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Calcar \Cal"car\, n.; L. pl. {Calcaria}. [L., a spur, as worn on
   the heel, also the spur of a cock, fr. calx, calcis, the
   heel.]
   1. (Bot.) A hollow tube or spur at the base of a petal or
      corolla.
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   2. (Zool.) A slender bony process from the ankle joint of
      bats, which helps to support the posterior part of the
      web, in flight.
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   3. (Anat.)
      (a) A spur, or spurlike prominence.
      (b) A curved ridge in the floor of the leteral ventricle
          of the brain; the calcar avis, hippocampus minor, or
          ergot.
          [1913 Webster] Calcarate