siphonostomata

from The Century Dictionary.

• noun In Crustacea:
• noun In Latreille's classification, the second family of his Pæcilopoda, divided into Caligides and Lernæiformes, the former of which is approximately equivalent to the modern order Siphonostomata, the latter to the Lernseoidea. All are parasitic crustaceans.
• noun An order of epizoic or parasitic crustaceans, having the thorax segmented, several pairs of limbs, three pairs of maxillipeds, and antennæ. It corresponds to the Caligides of Latreille. There are several families of these fish-lice. Also called Siphonostoma.
• noun In Mollusca, a division of prosobranchiate gastropods, having the lip of the shell notched, canaliculate, or tubular, for the protrusion of a respiratory siphon: contrasted with Holostomata.

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

• noun plural A tribe of parasitic copepod Crustacea including a large number of species that are parasites of fishes, as the lerneans. They have a mouth adapted to suck blood.
• noun plural An artificial division of gastropods including those that have siphonostomatous shells.