Tergal suture: the Y shaped dorsal suture on the head of many insect larvae.
"Explanation of Terms Used in Entomology" by John. B. Smith
Tergal margin straight, overlapping about one third of the entire width of the terga.
"A Monograph on the Sub-class Cirripedia (Volume 1 of 2)" by Charles Darwin
The tergal elements of the somites bearing the antennae, mandibles and maxillae appear to be represented by the head-shield or cephalite.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6" by Various
It is represented by a full-sized tergal plate in the Pseudo-scorpiones.
"Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 3" by Various