||Pyc`no*gon"i*da (?), n. pl. [NL., fr. Gr. &?; thick crowded + &?; knee.] (Zoöl.) A class of marine arthropods in which the body is small and thin, and the eight legs usually very long; -- called also Pantopoda.

&fist; The abdomen is rudimentary, and the triangular mouth is at the end of a tubular proboscis. Many of them live at great depths in the sea, and the largest of them measure two feet across the extended legs.