The Collaborative International Dictionary
Gnathostegite
Gnathostegite \Gna*thos"te*gite\, n. [Gr. gna`qos the jaw + ? a roof.] (Zo["o]l.) One of a pair of broad plates, developed from the outer maxillipeds of crabs, and forming a cover for the other mouth organs.
Wiktionary
gnathostegite
n. (context zoology rare English) One of a pair of broad plates, developed from the outer maxillipeds of crabs, and forming a cover for the other organs in the mouth.