n. In annelids, as the earthworm, a thick layer, below the cuticula, of reticulated or nucleated tissue, in the meshes of which is a copious transparent gelatinous substance. It is considered by some as probably representing both the dermis and the epidermis of other animals.n. In entomology, a soft cellular substance or tissue lining the abdominal wall of an insect, within the chitinous investment.