The following notes mostly concern the description of new species from East Africa in connection with renewed work on a check-list of the non-marine Mollusca of that area which has been in preparation during the past 25 years. A fairly complete manuscript has been available for many years but additional material and further research continually render it in need of revision. Previous notes in this series were published in Basteria, the last being Verdcourt (1978). A number of the professional photos have been kindly made by Mr. A. 't Hooft of the Department of Systematics and Evolutionary Biology of the University, Leiden; Dr. A. C. van Bruggen of the same university department has made the paper ready for the press. The following abbreviations are used in the text: BM, British Museum (Natural History), London; MRAC, Musée Royal d'Afrique Centrale, Tervuren; NM, National Museum, Nairobi (formerly Coryndon Museum); RMNH, Rijksmuseum van Natuurlijke Historie, Leiden. In the genitalia drawings the following abbreviations have been used: A - atrium; C - caecum; CD - common duct; CG - calcareous gland; Ε - epiphallus; F - flagellum; Ρ - penis; PA - penial appendage; PIL - pilaster; PR - penial retractor; S - spermatheca; SD - spermathecal duct; SP - spermatophore; U - uterus; V - vagina; VD - vas deferens; WI - wall 1; Wll - wall 2. 12. A NEW SPECIES OF RHACHISTIA (ENIDAE) FROM THE KENYA COAST In January 1958 I found on the Kenya coast opposite the island of Lamu a single specimen of a colourful enid snail which was unlike any I had seen before in East Africa. Attempts to name the species proved inconclusive. In November 1961 R. M. Polhill found another single specimen at Marafa, 40 km NW. of Malindi, some 125 km SSW. of my locality, which specimen differed in only slight details of the pattern and clearly belonged to exactly the same taxon. Since then no other material has turned up and I have decided to describe it