580 MR. E. A. SMITH ON THE GENUS MYODORA. [NoV. 16, 



Myodora striata, Q. & G., Hanley, Cat. Biv. Sh. pi. 12. f. 12. 



21. brevis. Woodward, non Sowerby, Manual Moll. pi. 23. f. 12. 



Hab. New Zealand. "Common in the north, rare in the south, 

 Dunedin" {Hutton, Manual of N.Z. MoUusca, 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 ' Con- 

 chologia 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, pi. 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 ligameutal 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, pi. 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, pi. 10. f. 13; Chenu, Man. de 

 Conch, vol. ii. p. 52, fig. 217. 



Non M. brevis, Woodward, Man. Moll. pi. 23. f. 12, = M. striata. 



Non M. brevis, H. & A, Adams, Gen. Rec. Moll. vol. iii. pi. 98. 

 f. 2-2a, = M. pandoriformis. 



Hab. Port Jackson {Stutchbury ^ Brenchley) ; Lane Cove, Farm 

 Cove, and Mossman's Bay (Anffas, P. Z. S. 1867); Cape Upstart 

 (Mus. Cuming) ; New Zealand {Bolton); Stewart Island (C. Traill) ; 

 Tasmania (22. G«<H«). 



The form of this species is subject to considerable variation. This 

 may be seen by comparing the figure in the Stutchbury Sale Cata- 

 logue 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 

 oblono-. 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 



