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Carina moderately bowed inwards, widening gradually downwards from the apex, of which a small portion is filled up solid, and must have projected freely; walls moderately thick; the two sides of the tectum are rather steeply inclined to each other, and meet in a central line, which is sub-carinated with a slightly prominent ridge; basal margin rectangularly pointed; parietes nearly fiat, about as wide as the tecta, in some specimens perpendicular, so as not to be visible when the valve is viewed from a central dorsal point; in others, very steeply splayed outwards; separated from the intra-parietes by a conspicuous rounded ridge, and from the tectum by a nearly equally large ridge, which has generally one, two, or three fine, longitudinal, raised lines on either one or both sides of it: in one specimen the whole surface was thus coarsely and obscurely lined. The intra-parietes are rather wide, extending to the basal margin of the parietes. Depth of valve, measured from the central crest to either inner edge, is about equal to the entire width, as measured from inner edge to edge. The depth compared with the width, though the most conspicuous character, varies a little. Inner edge of valve nearly straight. Length of longest specimen (in Mus. Bowerbank) i*6 o f an inch. This is the largest carina I have seen in any fossil cirripede.