\Ech`i*u*roi"de*a\, n. pl. [NL., fr. echiurus, the
name of one genus (Gr. ? an adder + ? tail) + -oid.]
(Zo["o]l.)
A division of Annelida which includes the genus {Echiurus}
and allies. They are often classed among the Gephyrea, and
called the {armed Gephyreans}.