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Keywords from Image Description:
A monograph on the subclass Cirripedia Figs. . NOMENCLATURE OF THE SHELL OF SESSILE CIRRIPEDE SHELL Fig Orifice of shell surrounded by the sheath Sheath formed by the alee and by portions of the upper and inner surfaces of the parietes Parietes Basis Radii Alae Basis In Balanus and many other genera the Rostrum and Rostrolateral