Pygidium

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Pygidium \Py*gid"i*um\, n.; pl. {Pygidia}. [NL., fr. Gr. ?, dim.
     of ? the rump.] (Zool.)
     The caudal plate of trilobites, crustacean, and certain
     insects. See Illust. of {Limulus} and {Trilobite}.
     [1913 Webster] Pygmy