TY - JOUR T1 - Notes on the non-marine molluscs of the island of Borneo 2. The genus Opisthostoma (Gastropoda Prosobranchia: Diplommatinidae), part 2 JF - Basteria Y1 - 1991 A1 - J.J. Vermeulen SP - 139 EP - 163 VL - 55 ER - TY - JOUR T1 - Notes on the non-marine molluscs of the island of Borneo. 6. The genus Opisthostoma (Gastropoda Prosobranchia: Diplommatinidae), part 2 JF - Basteria Y1 - 1994 A1 - J.J. Vermeulen SP - 73 EP - 191 VL - 58 ER -