balanoglossus

from The Century Dictionary.

• noun An extraordinary genus of invertebrate animals, the type not only of a family, Balanoglossidæ, but also of an order or even a distinct class of animals, Enteropneusta (which see).
• noun [lowercase] A member of the genus Balanoglossus.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl) A peculiar marine worm. See enteropneusta, and tornaria.