The Collaborative International Dictionary
Endostoma
Endostoma \En*dos"to*ma\, n. [NL., fr. Gr. ? + ?, ?, the mouth.] (Zo["o]l.) A plate which supports the labrum in certain Crustacea.
Wiktionary
endostoma
n. (context zoology English) A plate that supports the labrum in certain crustacea.