Proceedings of the General Meetings for Scientific Business of the Zoological Society of London 1901

Page 360

392 DR. H. L. JAMESON ON THE [Apr. 16, very inconstant form. The radius from the umbo to postero-ventral angle of shell is usually more distinct than the others and often different in colour. No two of the ten examples in the Museum are similarly coloured, all colours-black, brown, purple, red, pink, white, and yellow-being represented in all possible combinations. The interior of the lip is white with scattered red blotches, or golden yellow with dark brown markings, or cream-coloured with pale brown markings, or black with irregular white markings. The nacre has the yellowish-green tint characteristic of 31. panasescc. Measurements. Hinge 30 mm.; greatest antero-post. measure­ment 40 ; do. nacre 30 mm. Greatest dorso-ventr. measurement 35 mm. ; do. nacre 25 mm. Greatest antero-posterior measure­ment is very nearly on the ventral margin in some specimens. The sheli shows a strong tendency for the postero-ventral angle to be drawn out somewhat, as in Pteria s. s. or Electroma. This character, coupled with great obliquity and convexity, extra­ordinarily rich coloration, and unusual length of the ventral margin, should suffice to distinguish this somewhat aberrant species. Geographical Distribution. 10 specimens in B. M., 1885.9.19, nos. 13-22 ; found attached to pumice-stone floating off Mauritius (Robillard). SPECIES OF UNCERTAIN POSITION. Species 28. MARGARITIFERA NIGRA. Avicula nigra, Gould, 1850, p. 309. Singapore. Avicula nigra, Gould, 1852, pp. 438-9, pi. 40. fig. 554. Species 29. MARGARITIFERA VIDUA. Avicula vidua, Gould, 1850, p. 309. Fiji. Avicula vidua, Gould, 1852, p. 439, pi. 39. fig. 553. Species 30. MARGARITIFERA GLABRA. Avicula glabra, Gould, 1850, p. 310. New Zealand. Avicula glabra, Gould, 1852, pp. 442-3, pi. 39. fig. 552. Species 31. MARGARITIFERA PLACUNOIDES. Avicula plaeunoides, Reeve, 1857, sp. 68. Australia. Type in B.M. Species 32. MARGARITIFERA TEGFLATA. Avicida tecjidata, Reeve, 1857, sp. 17. Moreton Bay, Queens­land. Type in B.M. Species 33. MARGARITIFERA LACUNATA. Aviada lacunata, Reeve, 1857, sp. 29. New Holland. Type in B.M.