An analysis has been made of the locomotory movements and of the jumping escape reactions of certain hexapods, together with a description of their associated facilitating morphology. Common features shown by all hexapod gaits are due simply to the use of only three pairs of legs. Superimposed are features which are characteristic of each of the four apterygote classes and of die Pterygota. The associated morphology in each of these five classes is so distinct, and mutually exclusive, as to indicate a parallel evolution of the hexapodous state in the five classes, from multilegged animals with a common head type, differing from that of the Myriapoda. No one hexapod class could have been ancestral to any other. The morphological evolution of the Collembola has been associated with a hydrostatic jumping mechanism correlated with profound morphological peculiarities. The jumping gaits and the jumping reactions implemented by the abdomen in Thysanura Machilidae are also correlated with unique morphology. A taxon, the Uniramia, is proposed to include die Onychophora‐Myriapoda‐Hexapoda, the Uniramia ranking as one of the several arthropodan phyla, and the Onychophora, Myriapoda and Hexapoda form three subphyla of the phylum Uniramia. The conclusions are presented in § 10, but there is no separate sum