CLASS IV 



GASTROPODA 



567 



^ Family 2. Ringiculidae Meek. 



Inoperculate forms resemhling the Actaeonidae in having columellar folds. Creta- 

 ceoiis to Receiit. 



Ginulia Gray (Fig. 1061). Globose, inflated, spirally grooved or pimctate. Spire 

 Short ; aperture crescentic ; oiiter lip reflected and thickened. Columella and inner lip 

 with numerous transversa folds. Cretaceous. 



Subgenera : Avellana, Ringinella d'Orb. ; Eriptycha Meek ; Fortisia Bayan. Eocene. 



Ringicula Desh. (Fig. 1062). Small, ovoid to globose, thick-shelled, with mammil- 

 lated protoconch. Spire sbort ; Iwdy whorl large, usnally smooth. Aperture canal- 



-1 /; (' 



Fifi. 1061. 



A, Cinulia (Avellarm) incrassata (Mant.). Gault ; Perte du 

 Rhone. B, C. (Ringinella) lachryma Mich. Gault ; P'olkestone, 

 England. C, ('. {Eriptycha) demrtata Zekeli. Turonian ; Gosau, 

 Austria. 



## 



Fl(i. 10G2. 



Ringicula hoernesi 

 Seguenza. Miocene; 

 Steinabrunn, near 

 Vienna. 



iculate posteriorly, excavated anteriorly. Columellar border tliick 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. 



Pugnns Hedley. Cylindrical, with sunkeii spire. Recent. 



Family 3. Akeratidae Pilsbry. 



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

 Recent. 



Tertiary and 



Äkera Müller (Fig. 1063). 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. 



Family 4. Hydatinidae Pilsbry. 



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

 protoconch. Jura to Recent. 



Fia. 1063. 



Akera striate.lla Lam. 

 Oligocene ; Castel Gomberto, 

 near Vicenza. 



Hydatina Schumacher. 

 Pilsbry. Recent. 



Jura to Recent. Aplustrum Schumacher; Micromelo 



Family 5. Bullariida^ Pilsbry (emeud.). 



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

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



Bullaria Raf. {Bulla Linn.) (Fig. 1064). Oval, inflated, with sunken spire and 

 perforated apex. Aperture rounded posteriorly and anteriorly. Jura (?) to Recent. 



