Horton —7he Plhocene Mollusca of New Zealand. 69 
Trocuus CHATHAMENSIS, Hutton, Cat. Marine Moll. of N.Z. p. 36. 
(Plate vu. fig. 74.) 
Whorls flat, with five or six sub-nodulose spiral ribs, those at the keel and 
at the posterior margin of the whorl larger than the others; the base spirally 
striated ; axial cavity small, smooth. Height 8mm.; breadth 9mm. 
Locality. —W anganui. 
Genus CALLIOSTOMA. 
Key to the species. 
1. Base with a large callus. 
Penultimate whorl with 10-11 equidistant spirals C. cunningham. 
% 5 7-8 spirals, the pos- 
terior 5 or 6 much closer ... ... CC. ponderosum. 
2. Base with a small callus. 
Penultimate whorl with 8-10 equidistant spirals C. pelluctdum. 
3. Base without any callus. 
Penultimate whorl with 4 or 5 spirals... ... C. hodger. 
Bs 10 or 12 spirals .» C. punctulatum. 
CaLLiosToMA CUNNINGHAMI, Gray ; Reeve, Conch. Icon. fig. 6. 
Locality.—W anganui. 
Catuiostoma ponpERosuM, Hutton, Trans. N.Z. Inst. Vol. XVII. p. 322. 
(Plate vim. fig. 75.) 
Shell large, solid. Whorls 5 or 6, flattened, the periphery roundly angled ; 
with 7 or 8 spiral ribs, the anterior two distant, the others much closer. Suture 
distinct. Base with about 12 fine spiral ribs. Aperture rhomboidal ; the 
umbilical callus large. Height 35mm. ; breadth 43mm. 
Locality. —W anganui. 
bo 
CaLLiosToMa PELLUCIDUM, Valenciennes, Voy. Venus, Moll. pl. rv. fig. 
Locahty.—Wanganui, Petane. 
