486 



MOLLUSOA 



SUB-KINGDOM VI 



Family 2. Ringiculidae. 



Inoperculate forms resembling Actaeonidae in having columellar folds. Cretaceous 

 to Recent. 



Cinulia, Gray (Fig. 1012). Globose, inflated, spirally grooved or punctate. Spire 

 short ; aperture crescentic ; outer lip reflected and thickened. Columella and inner 

 lip with numerous transverse folds. Cretaceous. 



Sub-genera : Avellana, Ringinella, d'Orb. ; Eriptycha, Meek ; Fortisia, Bayan. Eocene. 



Ringicula, Desh. (Fig. 1013). Small, ovoid to globose, thick -shelled, with mamil- 

 lated protoconch. Spire short ; body whorl large, usually smooth. Aperture canali- 



Fio. 1012. 



A, Cinulia (Avellana) incrassata, Mant. sp. Gault ; Perte 

 du Rhone. B, C. (llinnhii'Jl,,) lachryma, Mich. Gault ; 

 Folkestone, England. C, C. (Eriptycha) decurtata, Zekeli. 

 Turonian. Gosau, Austria. 



FIG. 1013. 



Ringicula Hoernesi, 

 Seguenza. Miocene ; 

 Steinabrunn, near 

 Vienna. 



culate posteriorly, excavated anteriorly. Columellar border thick and callous ; the 

 columella arched, and furnished with from two to four plications. Outer margin 

 usually very thick, reflected, and occasionally denticulated within. Cretaceous to 

 Recent. 



Pugnus, Hedley. Cylindrical, with sunken spire. Recent. 



Family 3. Akeratidae. Pilsbry. 



Shell oval or cylindrical, thin and fragile, the spire low or concealed. Tertiary and 

 Recent. 



Akera, Miiller (Fig. 1014). Thin-shelled, flexible, with exposed, truncated spire. 

 Whorls separated from one another by deep sutures. Sutures 

 deep and prominent ; outer lip separated from the spire. 

 Eocene to Recent. 



Haminea, Leach. Oval, thin-shelled, brittle ; the spire 

 concealed. Tertiary and Recent. 



FIG. 1014. 



Akera striatella, Lam. 

 Oligocene ; Castel Gomberto, 

 near Vicenza. 



Family 4. Hydatinidae. Pilsbry. 



Globose or oval, with exposed, nearly level spire and tilted 

 nucleus. Jura to Recent. 



Hydatina, Leach, Schum. 

 Pilsbry. Recent, 



Jura to Recent. Aplustrum, Schum. ; Micromelo, 



Family 5. Bullidae. Pilsbry (emend.). 



Shell oval or sub-globose, involute, smooth. Spire sunken and concealed. Aperture 

 long, rounded anteriorly ; outer lip sharp. Marine. Jura to Recent. 



