nScaphognathite(Zoöl) A thin leafike appendage (the exopodite) of the second maxilla of decapod crustaceans. It serves as a pumping organ to draw the water through the gill cavity.
Century Dictionary and Cyclopedia
nscaphognathiteIn Crustacea, an appendage of the second maxilla, apparently representing a combined epipodite and exopodite. In the crawfish it forms a broadly oval plate or scaphoid organ, which continually bales the water out of the respiratory chamber, and so lets fresh water in. See cut at Podophthalmia (C, cd).