tagmata). In organisms with highly derived tagmata, such as the insects, much of the metamerism within a tagma may not be trivially distinguishable. It may have to be sought in structures that do not necessarily reflect the grouped metameric function (eg. the ladder nerve system or somites do not reflect the unitary structure of a thorax).

In addition, an animal may be classified as "pseudometameric", meaning that it has clear internal metamerism but no corresponding