864 PELECYPODA. [Filibranchia. 



"2. Mytilus canaliculus, Martyn, 1784. Plate 56, fig. 5. 



Mytilus canaliculus, Martyn, Un. Conch., ii, 1784, f. 78 ; Hanley, Cat. 

 Rec. Biv. Shells, 248. M. smaragdinus, Chemn. : Hutton, C.M.M., 77 ; 

 not of Chemnitz. M. latus, Lam. : C.M.M., 78 ; not of Lamarck. 

 M. latus, Chemnitz : Hutton, J. de Conch., 1878, 52 ; M.N.Z.M., 167 ; 

 P.L.S. N.S.W., ix, 529 ; Index, 94 : not of Chemnitz. 

 SMI 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 con- 

 vex ; the basal margin concave at its posterior half. Sculpture con- 

 sisting of numerous fine concentric growth-lines, crossed by very fine 

 and dense radial stria? ; well-preserved specimens usually show con- 

 centric 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., 172mm.; dorso-ventral, 70mm.: thick- 

 ness, 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 Maerocustis 

 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 50mm. on the wharf-piles in Auckland Harbour in 



one year. 



Maori. Kuku, kutai (fide Captain Bollons). 

 Fossil in the Miocene and Pliocene. 



Subgen. 3. AULACOMYA, Morch, 1853. 



Aulucomya, Morch, Cat, Conch. Yoldi, pt. 2, 1853, 53 ; von Ihering, P. Mai. S., 



iv, 87 ; Jukes-Browne, I.e.., vi, 218. Type : Mytilus mageUantcus, Lam. 



Shell always ribbed or furrowed. Umbones terminal, elongated, 



and often projecting beyond and in front of the anterior side, which 



