[Amphipoda] (Abbr. MX) this pair of appendages bears simple outer and inner lobes (=plates). In gammarids a row of setae on the dorsal face of the inner lobe (or their absence) is important for systematics. In hyperiids the maxilla II may be rudimentary or absent (Lycaeidae, Oxycephalidae).

Alternative form for Maxilla II : MX II (abbrev.).