Schema comparing the ventral nervous systems of Onychophora, Tardigrada and Arthropoda. Hatched lines indicate the position of legs. Note the anteriorly shifted arrangement of ganglia relative to the legs in tardigrades and arthropods. Diagrams of the onychophoran and arthropod nervous systems according to Mayer and Harzsch [26,27] and Richter et al. . Abbreviations: al, anterior leg nerve; cf, central fibre mass; cn, somata-free connective; co, commissure; ga, ganglion; ip, interpedal commissure; lv, leg nerve; nc, nerve cord; ne, neuropil; pl, posterior leg nerve.
Mayer et al. BMC Evolutionary Biology 2013 13:230 doi:10.1186/1471-2148-13-230