The Western Indian Ocean species gemmuliferus differs from the N.albescens in the following features: The sculpture is coarser in gemmuliferus, particularly on the body whorl where axial ribs number from 20-25; the majority of specimens have intermediate narrow fillets which separate the main rows of gemmules on the body whorl. The protoconch is glassy-white or cream and all post- embryonic whorls lack the violet or purplish-brown colouring of the Pacific albescens. The body whorl is usually banded with brown and the interior of the aperture is banded with purple-brown. The oper- culum is brown and serrate at the margins.

TYPE LOCALITY. Burias I, Philippines, 11 m = error! (gemmuliferus); none (isabellei Reeve; fenestrata); Massawa, Red Sea, 11 m; Archico; Arafali, 10 m; Rathmat (gestroi). Mauritius is here designated as the type locality of N.albescens gemmuliferus (specimens in AIM, AMS and ZMC). DISTRIBUTION. From the Red Sea and the Persian Gulf to South Africa and the Andaman Is. In clean and muddy coral sand, from the intertidal zone to a depth of 33 m. Type specimens. Two syntypes of N.albescens gemmuliferus (A.Adams), are in the British Museum (N.H.), London, No. 197338, and the syntype measuring length 11.7 mm, width 6.8 mm, is here selected as the lectotype. (P1.8, Fig.2) The holotype of N.fenestratus var. gestroi Bisacchi, length 14.0 mm, is in the Museo Civico Storia Naturale, Genova. The type of Nassa fenestrata Marrat (and of N.isabellei Reeve), has not been located. Material examined. RED SEA: Dahlak Archipelago, 15°08'N & 40°18'E, 9 m; Dahab; Eilat, Gulf of Aqaba; Museri I; Hawakil Bay, Eritrea, 13°17'N & 40°20'E, 18-24 m; Nuweiba; Ras Muhamad; Marsa el Ef, Gulf of Aqaba; N.of Fara'un I; N.of Taba, Gulf of Aqaba; Sharm-el-Moya, Gulf of Aqaba; Marsa-el-Murach, Gulf of Aqaba (all TAU); Jiddah Harbour (USNM); PERSIAN GULF: Pearl Banks, 3 km S.S.E. of Quais I, 3-4 m; N.E. of Bahrein, 26°38'N & 51°03'E, 20 m; 4 km E.S.E. of Bustani, 5-6 m; Stiffe's Bank, 26°27'N & 53°08'E, 33 m (all ZMC); Tarut Bay (coll. Powell); Masirah I (coll. Rogers); Ras Tanura (USNM); EAST AFRICA: Raskamoni reef, Dar-es-Salaam (coll.Eker); Kepwani, 2 km N. of Uzi I, S.W. Zanzibar; Chwaka village, E.Zan- zibar (both AIM); Tiwi River, S. of Mombas (ZMC); near Mombassa, Kenya (USNM); Dissei I, Ethiopia, 2 m (Natal Mus.); MADAGASCAR: Pt. Fievre, S. of Nossi-Be (AIM); Tulear (SMOM); Nossi-Be (USNM); SOUTH AFRICA: Durban, Natal (AIM; USNM); SEYCHELLES IS: (USNM); Bay Ternay, Mahe I (coll. Dale); MAURITIUS: Graved Bay; Black River, 9-18 m; Cannonier's Pt. (all ZMC); Flic-Flac (AIM); Arsenal Bay (AMS); REUNION I: Lagon de la Saline (coll.Martin); INDIA: Indian Seas (ZSI); South India (ZSI); ANDAMAN IS: (AMS; USNM; ZSI).