The Collaborative International Dictionary of English v.0.48:

Thaliacea \Tha`li*a"ce*a\, n. pl. [NL. See Thalia.] (Zool.)
   A division of Tunicata comprising the free-swimming species,
   such as Salpa and Doliolum.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Animal \An"i*mal\, a. [Cf. F. animal.]
   1. Of or relating to animals; as, animal functions.
      [1913 Webster]

   2. Pertaining to the merely sentient part of a creature, as
      distinguished from the intellectual, rational, or
      spiritual part; as, the animal passions or appetites.
      [1913 Webster]

   3. Consisting of the flesh of animals; as, animal food.
      [1913 Webster]

   Animal magnetism. See Magnetism and Mesmerism.

   Animal electricity, the electricity developed in some
      animals, as the electric eel, torpedo, etc.

   Animal flower (Zool.), a name given to certain marine
      animals resembling a flower, as any species of actinia or
      sea anemone, and other Anthozoa, hydroids, starfishes,
      etc.

   Animal heat (Physiol.), the heat generated in the body of a
      living animal, by means of which the animal is kept at
      nearly a uniform temperature.

   Animal spirits. See under Spirit.

   Animal kingdom, the whole class of beings endowed with
      animal life. It embraces several subkingdoms, and under
      these there are Classes, Orders, Families, Genera,
      Species, and sometimes intermediate groupings, all in
      regular subordination, but variously arranged by different
      writers.

   Note: The following are the grand divisions, or subkingdoms,
         and the principal classes under them, generally
         recognized at the present time:
         Vertebrata, including Mammalia or Mammals, Aves or
         Birds, Reptilia, Amphibia, Pisces or Fishes,
         Marsipobranchiata (Craniota); and Leptocardia
         (Acrania). Tunicata, including the Thaliacea, and
         Ascidioidea or Ascidians. Articulata or Annulosa,
         including Insecta, Myriapoda, Malacapoda, Arachnida,
         Pycnogonida, Merostomata, Crustacea (Arthropoda); and
         Annelida, Gehyrea (Anarthropoda).
         Helminthes or Vermes, including Rotifera,
         Ch[ae]tognatha, Nematoidea, Acanthocephala, Nemertina,
         Turbellaria, Trematoda, Cestoidea, Mesozea.

WordNet (r) 3.0 (2006):

Thaliacea
    n 1: small class of free-swimming tunicates; sometimes
         classified as an order [syn: Thaliacea, class
         Thaliacea]