Abstract
Study of a series of embryos showed that the spiroboloid leg arrangement (1 pair of legs on each of the first 5 segments) is derived from the typical leg arrangement (no legs on segment 1, 1 pair on segments 2 through 4, and 2 pairs on segment 5) by a shifting forward one segment of the first four pairs of legs.A careful re‐examination of the literature, especially papers by Robinson ('07), Silvestri ('03, '49), Pflugfelder ('32), and Manton ('61), combined with observations of Narceus embryos led to the conclusion that (1) the anterior body segments are primatively single (2) the gnathochilarium is composed of only one pair of mouthparts, the diplopod head having but two gnathal segments, and (3) the intercalary segment is present in the Diplopoda.