siphonata

from The Century Dictionary.

• In entomology, same as Hemiptera.
• In conchology, a division of lamellibranch or bivalve mollusks, containing those which have one or two siphons.

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

• noun plural (Zoöl.) A tribe of bivalve mollusks in which the posterior mantle border is prolonged into two tubes or siphons. Called also Siphoniata. See siphon, 2 (a), and quahaug.