podostomata

from The Century Dictionary.

• A class of Arthropoda, composed of the orders Trilobita and Merostomata (the latter containing the Xyphosura, Synziphosura, and Eurypterida): so called from the foot-like or ambulatory character of the mouth-parts. They are an ancient generalized type, represented at the present day by the king-crabs only.

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

• noun plural (Zoöl.) An order of Bryozoa of which Rhabdopleura is the type. See rhabdopleura.