cephalic shield
From ZooTerms (Dictionary of Invertebrate Zoology)
cephalic shield: 1. (Arthropoda: Crustacea) A chitinous, somewhat calcified covering of the head region formed of fused tergites of cephalic somites, commonly having pleura.
2. (Mollusca: Gastropoda) In Opisthobranchia, an expanded thickening of the dorsal surface of the head that may at times extend dorsally over the back.
