The Collaborative International Dictionary of English v.0.48:

Tubularia \Tu`bu*la"ri*a\, n. [NL.] (Zool.)
   A genus of hydroids having large, naked, flowerlike hydranths
   at the summits of long, slender, usually simple, stems. The
   gonophores are small, and form clusters at the bases of the
   outer tentacles.
   [1913 Webster]