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Show 580 MR. E. A. SMITH ON THE GENUS MYODORA. [Nov. 16, Myodora striata, Q. & G., Hanley, Cat. Biv. Sh. pl. 12. f. 12. M. brevis, Woodward, non Sowerby, Manual Moll. pl. 23. f. 12. Hab. New Zealand. "Common in the north, rare in the south, Dunedin" (Hutton, Manual of N.Z. Mollusca, p. 137). This is the largest species of the genus. The concentric striae on the flat valve are comparatively fine, and generally less conspicuous than as represented by the figures in the 'Astrolabe' and the 'Conchologia Iconica,' the latter depicting a shell with the angle formed by the dorsal margins exceptionally acute. The sculpture of the deep valve is rather coarser than that of the other valve. 2. MYODORA ROTUNDATA, Sowerby. Myodora rotundata, Sowerby, P. Z. S. 1875, p. 129, pl. 24. f. 8. Myodora rotunda, Hutton (as_of Sowerby), Manual N.Z. Moll. 1880, p. 137. Hab. New Zealand. This species differs from M. striata in having the convex or deep valve much deeper, the hinder dorsal margin proportionally shorter, less incurved and more sloping, the ligamental pit much smaller, and the contour of the shell more rounded. 3. MYODORA BREVIS (Sowerby). Pandora brevis, Sowerby, Appendix to Stutchbury's Sale Cat. p. 3, pl. f. 2. Anatina brevis, Stutchbury, Zool. Journ. v. p. 99, tab. Suppl. 43. f. 1, 2. Myadora brevis, Reeve, P.Z.S. 1844, p. 93; id. Con. Icon. f. 7a-b; Hanley, Rec. Biv. Shells, pl. 10. f. 13; Chenu, Man. de Conch, vol. ii. p. 52, fig. 217. Non 31. brevis, Woodward, Man. Moll. pl. 23. f. 12, = M. striata. Non M. brevis, H. & A. Adams, Gen. Rec. Moll. vol. iii. pl. 98. f. 2-2a, = M. pandoriformis. Hab. Port Jackson (Stutchbury $• Brenchley) ; Lane Cove, Farm Cove, and Mossman's Bay (Angas, P. Z. S. 1867) ; Cape Upstart (Mus. Cuming) ; New Zealand (Bolton); Stewart Island (C. Traill) ; Tasmania (R. Gunn). The form of this species is subject to considerable variation. This may be seen by comparing the figure in the Stutchbury Sale Catalogue with that in the 'Zoological Journal.' The series of specimens in the Museum, too, indicate how variable the species is with regard to outline, the apical angle in some being much more acute than in others. The microscopic sculpture consists of a very minute granulation, the granules being of unequal sizes and frequently transversely oblong. This granulation is coarser than in the other species of the genus; and the almost total absence of the radiating microscopic lines obtaining in all of them is remarkable. The Tasmanian specimens are peculiar on account of the greater coarseness of the concentric raised ridges; but in other respects |