MILLIPEDE  , the popular name of the best known members of a

group of the Arthropoda, scientifically known as Diplopoda, and formerly united with the Chilopoda (see CENTIPEDE), the Pauropoda and the Symphyla as an order of the class Myriapoda . This classification, however, has of late years been abandoned on account of the recognition of closer affinity between the Chilopoda (centipedes) and the Hexapoda (insects) than between the Chilopoda and Diplopoda . By modern writers the above-mentioned groups of " tracheate " Arthropoda are either regarded as independent classes of this phylum Arthropoda, or associated in two superclasses, the Opisthogonea or Opisthogoneata for the Chilopoda and Hexapoda; and the Prosogonea or Prosogoneata for the Diplopoda, Pauropoda and Symphyla . The structural character upon which these superclasses are based is the position of the generative apertures which open anteriorly in the Prosogonea and posteriorly in the Opisthogonea . Although the Pauropoda and Symphyla are not, strictly speaking, Diplopoda, these three groups of prosogoneate arthropods are here for convenience considered together .