Sensory pittings: deep pits or punctures through the surface, which may or may not bear pegs, bristles or seta, and may be open or covered by a membrane; serving as organs of perception for sounds or smells.
Septa, Septula: in Odonata, the triangular area of the mesonotum before the insertion of the primaries: = calli axillary.
Septum: an internal division of a body cavity.
Sequence: the order in which things follow; e.g. species or genera.
Seriatim: placed in longitudinal rows.
Sericeous: silky: clothed with very dense minute hair which gives a silky lustre.
Sericterium -ies: the silk producing gland or glands in caterpillars: the spinning structures.
Series: a group of species, genera or families, arranged to show agreement in a common character which is not of sufficient importance to warrant the next higher division.
Serific glands: are these which produce a thick, mucous-like secretion which, on hardening, forms silk.
Serosa: the outer membrane that envelops the forming embryo, the amnion and the remainder of the egg.