n pl :  a subclass of Nematoda comprising worms in which the sensory organs are often bristlelike, phasmids are lacking or greatly reduced, the lateral cervical papillae are absent, and the sensory depressions situated laterally at the anterior end are usu. modified - compare PHASMIDIA  .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.