Part of gill chamber above (external to ) gills [Moore and McCormick, 1969].
(Order Decapoda):
In each branchial chamber in cephalothorax, space above (exterior to) gills, i.e., between gills and lateral wall of carapace. See: hypobranchial space [Stachowitsch, 1992].
Crustacea glossary. Natural History Museum of Los Angeles County. 2011.