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“Mytilus canaliculus, Martyn, 1784. Plate 56, fig. 5.
Shell attaining a large size, wedge-shaped, oblong, base flattened, with a distinct angle extending from the umbo to the lower end of the posterior margin, with concentric growth-lines, yellowish-green. Beaks distant, sharply pointed, and curved downward. Anterior end sharply pointed, the anterior part of the dorsal margin ascending, convex, and forming an obtuse angle with the posterior, slightly descending, and convex part of the margin. Posterior end compressed, regularly convex; the basal margin concave at its posterior half. Sculpture consisting of numerous fine concentric growth-lines, crossed by very fine and dense radial striæ; well-preserved specimens usually show concentric ridges composed of numerous sharply pointed triangular and but slightly raised areas; triangular area below the beaks with several sharply raised and interlocking ribs. Epidermis thick, horny, lightly shining. Colour usually yellowish-green, sometimes light yellowish-brown on the base, dark and bright green with numerous brown radial rays on the upper parts; young shells are mostly light yellow, with an elliptical brown area on the anterior part of the base, and with bright green on the anterior upper end. Interior purplish-white, iridescent. Margins smooth, sharp, the epidermis extending some distance beyond them. Hinge-plate moderately broad, curved, with 1 or 2 sharp teeth. Ligament external, but very deep-seated, and of considerable length. Adductor-scar only 1, posterior, large and oval; 3 byssus retractor scars, the anterior narrow and oblong, above the beaks, the median below the dorsal angle, and the posterior in front and above the adductor-scar, both united. Pallial line simple.
Diameter – Ant.-post., 172 mm.; dorso-ventral, 70 mm.: thickness, 53 mm. (a fairly large specimen).
Anatomy.—Alex. Purdie, as quoted for M. edulis.
Hab. – Throughout New Zealand, on exposed rocks and wharf-piles, and in deeper water, where frequently the roots of Macrocystis are fixed on it. Kermadec islands. Also Tasmania. Brought to England by Captain Cook.
Remark.—According to my observations, this species will grow to a length of about 50 mm. on the wharf-piles in Auckland Harbour in one year.
Maori.—Kuku, kutai (fide Captain Bollons).
Fossil in the Miocene and Pliocene.”