Ichthus for l e'sous, CH ristos, TH eou U ios, S oter. This notarica is found on many seals, rings, urns,
and tombstones, belonging to the early times of Christianity, and was supposed to be a "charm" of
mystical efficacy.

Apparently not related to "ictus"

c[tus 7ik4t!s8
n.,
pl. 3tus[es or 3tus 5L, a blow, stroke, metrical stress < pp. of icere, to strike, hit, beat < IE base *aik3, *ik3, spear, to strike with a sharp weapon > Gr aichmc, a spear6
1 rhythmic or metrical stress, or accent
2 Med. a convulsion, stroke, or sudden attack


I have been unable to find definition of "notarica"