SUB-ORDER B RHIPIDOGLOSSA 449 
Family 9. Delphinulidae. Fischer. 
Shell turbinate or discoidal, usually thick, nacreous internally, and ornamented 
externally with spines, ribs, or folds. Aperture circular, peristome entire; outer lip 
usually expanded or thickened. Operculum horny, often strengthened by a thin calcareous 
outer layer. Silurian to Recent. 
Craspedostoma, Lindstrém. Globose, narrowly umbilicate, with short spire, and 
large transversely striated or cancellated body whorl. Inner lip with an alar process 
at the end of the columella. Silurian. C. elegantulum, Lindstrém. 
Crossostoma, Morr. and Lye. (Fig. 824). Depressed turbinate, smooth, without 

Fic. 825, 
~ OF O20 
Fic. $24. Liotia Gervillei, Fic. 826. 
Crossostoma —_re- Desh. sp.  Caleaire Delphinula searegata, 
flexilabrum, d’Orb. Grossier ; Haute- Heb. Des]. Callovian ; Delphinula scobina, 
sp. Middle Lias; ville, near Valogne, Montreuil - Bellay, Brongt. sp. Oligocene ; 
May, Calvados. France. Maine-et-Loire. Gaas, near Dax, France. 
umbilicus. Spire short, aperture round, narrowed by a callus. Outer lip somewhat 
reflexed. Trias and Jura. 
Liotia, Gray (Fig. 825). Depressed turbinate, with transverse swellings. Aperture 
thickened by a callous rim. Jura to Recent. 
Delphinula, Lam. (Angaria, Bolt.), (Figs. 826, 827). Depressed turbinate, um- 
bilicate. Whorls scaly, spinous, or spirally ornamented. Aperture. circular, lip 
without thickening. Trias to Recent. 
Family 10. Trochonematidae. Zittel. 
Shell pyramidal, turbinate, or discoidal, dextral or sinistral, with internal nacreous 
layer. Whorls convex, with one or more longitudinal keels, and slightly undulating trans- 
verse striae or ribs. Aperture rounded, sometimes 
with faint notch. Operculum unknown, presumably 
horny. Marine. Cambrian to Cretaceous. 
This extinct group is very abundant in the 
Palaeozoic, and notably so in Jurassic rocks. The 
shells, as a rule, are highly ornamented, and have 
been associated by some with the Littorinidae, by 
others with the Turbinidae or Purpurinidae. They 
form a distinct family, which is best placed in the 
neighbourhood of the Turbinidae and Trochidae. 
Trochonema, Salter. Pyramidal to turbinate, 

ae : : Fic. 828. 
deeply umbilicate, longitudinally keeled and trans- __,, wae Fi. 829. 
3 S J a> Eunema strigi- 
versely striated. Aperture round; the umbilicus lata, Salter. Or- Amberleya carpitanett, 
he Bey Jey 1; ay X: ae dovician; Pau- Minst. Upper jas ; 
surrounded by a keel. Cambrian to Silurian. quette Falls, La Verpilliere, near 
Kunema, Salter (Fig. 828). Pyramidal, with Canada. Lyons, France. 
acute, elongate spire, and no umbilicus. Whorls 
with two or more spiral keels, and strong transverse striae. Aperture oval, slightly 
notched anteriorly. Ordovician to Devonian. 
Amberleya, Morr. and Lye. (Hucyclus, Deslongeh.), (Fig. 829). Turbinate to 
VOL. I 2G 
