Fossil terrestrial gastropods have proven to be reliable indicators of palaeoenvironments. Fossil assemblages from the Early Miocene of East Africa have similar compositions to extant snails assemblages from the same region, although there are some notable absences in the fossil record. The fossil gastropods from the Legetet Formation, near Koru, Western Kenya, comprises ca. 50000 specimens belonging to at least 48 taxa. Such a rich assemblage rivals the diversity in optimal extant snail territories, such as tropical forest. The present note describes and interprets the Early Miocene Legetet Gastropoda. They reveal that the region was covered in perennially humid forest at the time of deposition, and that it was an upland more than 1200 metres above sea-level. Snails were evidently breeding at the site, as shown by the abundance and variety of snail eggs found in the deposits.

Introduction 7
Systematic descriptions 12
Family Pupillidae 12
Genus Afripupa Pilsbry & Cooke, 1920 12
Species Afripupa kenyensis sp. nov. 12
Genus Lauria Gray 1840 12
Species Lauria indet. 12
Family Chondrinidae 13
Genus Gastrocopta Wollaston, 1878 13
Species Gastrocopta indet. 13
Family Cerastidae 14
Genus Conulinus Von Martens, 1895 14
Species Conulinus verdcourti sp. nov. 14
Genus Edouardia Gude, 1914 15
Species Edouardia cf. alycaeoides Verdcourt, 1957 15
Species Edouardia mfwanganensis Verdcourt, 1963a 16
Family Ferussaciidae 17
Genus Micropeas Connolly, 1923 18
Species Micropeas brooksi sp. nov. 18
Micropeas cf. euphues Connolly, 1923 19
Genus Cecilioides Férussac, 1814 19
Species Cecilioides senutae sp. nov. 19
Family Subulinidae 20
Genus Krapfiella Preston, 1911 21
Species Krapfiella angusta Verdcourt, 1963b 21
Genus Kenyaella gen. nov. 23
Species Kenyaella koruensis sp. nov. 23
Genus Subulona Von Martens, 1889 25
Species Subulona mioegregia sp. nov. 25
Genus Oreohomorus Pilsbry, 1919 26
Species Oreohomorus sp. 26
Genus Subuliniscus Pilsbry, 1919 26
Species Subuliniscus sp. indet. 26
Genus Pseudopeas Putzeys, 1899 28
Species Pseudopeas koruensis sp. nov. 28
Genus Curvella Chaper, 1885 28
Species Curvella procampyla sp. nov. 28
Species Curvella cheptumoae sp. nov. 29
Genus Opeas Albers, 1850 29
Species Opeas gommeryi sp. nov. 29
Family Achatinidae 30
Genus Tholachatina Bequaert, 1950 30
Species Tholachatina leakeyi (Crowley & Pain, 1963) 30
Genus Burtoa Bourguignat, 1889 32
Species Burtoa nilotica verdcourti Crowley & Pain, 1959 32
Family Streptaxidae 33
Genus Artemonopsis Germain, 1908 34
Species Artemonopsis miocenica (Verdcourt, 1963a) 34
Genus Gonaxis Taylor, 1877 35
Species Gonaxis miocraveni sp. nov. 35
Genus Pseudogonaxis Thiele, 1932 36
Species Pseudogonaxis protocavalii (Verdcourt, 1963a) 36
Species Pseudogonaxis legetetensis nov. 37
Genus Edentulina Pfeiffer, 1856 39
Species Edentulina rusingensis Verdcourt, 1963a 39
Genus Marconia Bourguignat, 1889 39
Species Marconia elegans sp. nov. 39
Genus Orthogibbus Germain, 1919 41
Species Orthogibbus superbus sp. nov. 41
Genus Streptostele Dohrn, 1866 42
Species Streptostele indet. 42
Genus Primigulella Pilsbry, 1919 42
Species Primigulella miocenica Verdcourt, 1963a 42
Species Primigulella koruensis nov. 42
Genus Gulella Pfeiffer, 1856 44
Species Gulella moja sp. nov. 44
Species Gulella mbili sp. nov. 46
Species Gulella tatu sp. nov. 46
Species Gulella nne sp. nov. 47
Species Gulella tano sp. nov. 48
Species Gulella sita sp. nov. 48
Genus Silvigulella Pilsbry, 1919 50
Species Silvigulella palaeoshandae sp. nov. 50
Genus Haplonepion Pilsbry, 1919 50
Species Haplonepion naggsi sp. nov. 50
Family Charopidae 51
Genus Trachycystis Pilsbry, 1892 52
Species Trachycystis chancogneae sp. nov. 52
Species Trachycystis palaeokempi sp. nov. 53
Species Trachycystis legetetana sp. nov. 53
Family Urocyclidae 54
Genus Koruella gen. nov. 54
Species Koruella magnifica sp. nov. 54
Genus Crenatinanina Germain, 1920 56
Species Crenatinanina palaeokempi sp. nov. 56
Genus Trochonanina Mousson, 1869 57
Species Trochonanina mioelgonensis sp. nov. 57
Genus Thapsia Albers, 1860 58
Species Thapsia senutae sp. nov. 58
Family Vitrinidae 60
Genus Calidivitrina Pilsbry, 1919 60
Species Calidivitrina vanbruggeni sp. nov. 60
Family Halolimnohelicidae 61
Genus Mikenoella Preston, 1914 61
Species Mikenoella palahena sp. nov. 61
Genus Elgonella Preston, 1914 62
Species Elgonella aequatorialis sp. nov. 62
Summary and conclusions 63
Acknowledgements 66
References 67