'Tetractinellida' definitions:

Definition of 'Tetractinellida'

From: GCIDE

Tetractinellida \Te*trac`ti*nel"li*da\, n. pl. [NL., from Gr. te`tra- tetra- + ?, ?, ray, spoke.] (Zool.) A division of Spongiae in which the spicules are siliceous and have four branches diverging at right angles. Called also Tetractinellinae. [1913 Webster]