A division of Arachnoidea, including the daddy
   longlegs or harvestman (Phalangium) and many similar kinds. They have
   long, slender, many-jointed legs; usually a rounded, segmented abdomen;
   and chelate jaws. They breathe by tracheae. Called also Phalangides,
   Phalangidea, Phalangiida, and Opilionea.