Synonymous: words of different derivation applied to the same conception.

Synthlipsis: the basal constriction of the notocephalon in Notonectids.

Syntype: = co-type; q.v.

Syringe: in Hemiptera, a chamber into which the salivary ducts open and by means of which the secretion is forced forward between the seta or lancets.

System: an order of arrangement.

Systematic: in definite order, or arranged according to a system.

Systole: that regular contraction of the heart that sends the blood outward: see diastole.

[T]

T. A. line: transverse anterior line; crosses the primaries of certain moths one-third or less from the base: = antemedial line.

Tactile: used for touching; an organ that has the sense of touch.