456 



MOLLUSCS 



SUB-KINGDOM VI 



Family 1. Bulimidae. Fischer. 



Small, polished, elongate-conic shells, with ovate apertures '; the axis often distorted ; 

 nucleus dextral. Trias to Recent. 



Eulima, Risso (Fig. 861). Turreted, smooth, lustrous, 

 without umbilicus. Trias to Recent. 



Niso, Risso (Fig. 862). Like the last, but with deep 

 umbilicus reaching to the apex. Trias to Recent. 



Family 2. Pyramidellidae. Gray. 



Shell turreted to elongate-oval. Aperture oval, an- 

 teriorly rounded, or with faint canal; outer lip sharp. 

 Operculum horny, spiral. Marine. Cambrian to Recent. 



The nucleus consists of several whorls, and in 

 Palaeozoic and Mesozoic forms is coiled in the same 

 direction as the remainder of the shell. But in the 



FIG. 861. 



A, Eulima, sub- 

 ulata, Don. Plio- 

 cene ; Coroncina, 

 Tuscany. B, E. 

 polita, Linn. 

 Miocene; Nieder- 

 leis, Moravia. 



FIG. 862. 



Rome ' 



Niso cburnea, 

 Risso. Plio- 

 cene ; Monte younger and more typical genera it is heterostrophic, 



near distinctl 7 separated from the rest of the shell, and often 

 stands at an angle with the adult spire. It is question- 

 able whether forms older than the Cenozoic can be retained in this family ; Fischer 

 places most of them in a new family, entitled Pseudomelaniidae. 



Macrocheilus, Phil. (Macrochilina, Bayle ; Strobaeus, de Kon.), (Fig. 863). Elongate.- 

 oval, without umbilicus, smooth or with slightly curved growth- 

 lines. Spire acuminate, only moderately high ; last whorl 

 large. Aperture angular posteriorly, sometimes 

 with shallow anterior canal. Inner lip with 

 weak anterior folds. Silurian to Trias. 



? Ptychostoma, Laube ; ? Undularia, Koken. 

 Trias. 



Loxonema, Phil. Turreted, whorls arched, 

 with S- shaped growth -lines. Sutures deep; 

 aperture higher than wide, with shallow canal. 

 Silurian to Trias ; particularly 

 abundant in the Carboniferous. 

 Koken. Like 



FIG. 864. 



Zygopleura, 

 the last, but whorls with sharp, 

 slightly curved transverse ribs, 

 or transverse nodose keel. De- 

 vonian to Lower Cretaceous. 



FIG. 863. 



Pseudomelania 

 Heddingtonensis, 

 Sowb. sp. Ox- 

 fordian ; France. 

 Bands of original 

 coloration still 

 showing. 



Macrocheilus arculntn^. 

 Schloth. sp. Middle De- 

 i -TV i / r> -j.i 7 vonian ; Paffrath, near 



Bourget^a, Desh. (Ptthodea, cologne. 

 de Kon.). Large, elongate-oval 



to turreted, with large, inflated body whorl. Surface 

 marked with spiral striae or furrows. Carboniferous 

 and Upper Jura. 



Pseudomelania, Pictet (Chemnitzia, p.p. d'Orb.), 

 (Bayania) ladea, (Fig. 864). Turreted, with numerous, almost flat 





FIG. 865. 

 Psevdomelania 



Lam. 



caire 



sp. Cal- 

 Grossier 



whorls, and slightly impressed sutures. Surface 

 Grignon, near smooth, or marked by fine growth -lines ; aperture 



rounded anteriorly, or with faint canal. Umbilicus 

 wanting ; rarely an umbilical fissure present. Very abundant in the Trias and Jura, 

 less so in Cretaceous and Eocene ; probably present also in the Carboniferous. 



Coelost 



Sub-genera : Oonia, Microschiza, Gemm. ; Hypsipleura, Anoptychia, Koken. Trias and Jura. 

 lostylina, Eustylus, Spirostylus, Kittl. Trias. Bayania, Munier-Chalm. Eocene. (Fig. 865.) 



