566 



MOLLUSCA 



PHYLUM TI 



Columella thick, with one strong, spiral, slightly oblique plication. Upper Cretaceous 



to Recent. 



Adelactaeon Cossni. {Myonia Adams). Shell with sinistral protoconch, the latter 

 not very large. Whorls decussated by fine striae, growth -lines 

 inconspicuous. Columella slightly excavated, and carrying a 

 small but well-marked plication. Miocene of France and Ger- 

 many, and Recent. 



Fio. 1U56. 



Actaeonina myosotis 

 Buv. Coral-Rag; St. 

 Miliiel, Meuse. "-/i 

 (after Buvigiiier). 



Fig. 1055. 



Actaeonina dnrmoisiana 

 d'Orb. Coral-Bag; Val- 

 fin, Aiii. 



Fio. 1067. 



Cyltndrites acntus 

 (Sowerby). Great 

 Oolite; Minchin- 

 haiupton, England. 



Fifi. 1058. 



Actaeonelln girjantca Sowb. Turonian ; 

 Griinbach, Lower Austria. 



Actaeonina d'Orb. {Orthostoma Desh.) (Figs. 1055, 1056). Shell ovoid to fusiform, 

 usually smooth, rarely spirally striated. Spire conical, body whorl very large, 

 narrowing toward the base. Columella straight, without folds. 

 Outer lip sharp. Carboniferous to Recent. 



Subgenera : Euconactaeon, Conactacon Meek. 

 Lias. Douvilleia Bayle. Tertiary. 



Cylindrites Fer. (Fig. 1057). Cylindrical- 

 ovoid with short spire. Columella with an 

 anterior fold. Trias to Cretaceous. 



Bullina Fer. Jura to Recent. CyUndro- 

 hnllina v. Amnion. Trias and Lias. Etallonia 

 Desh. Jura and Tertiary. Bullinida Beck. 

 Jura to Recent. 



Actaeonella d'Orb. (Figs. 1058-1060). 



Thick -shelled, inflated, smooth. Spire short; 



columella thickened anteriorly, with three 



sharp folds. Very profuse in the Middle and 



Una) laevis Sowb. Upper Cretaceous ; maximum distribution in 

 Turonian, Gcsau. , ■, tt • • ^ t • ^ c J.^ ^.^ 



tne Hippurite Limestone oi the Alps. 



Fic!. ]0r,9. 



Actaeonella volnta 

 Goldf. Turonian; 

 Gams, Styria. 



Fio. 1060. 

 Actaeonella (Volrn- 



Subgenus 

 Cretaceous. 



Volmilina Stol. (Fig. 1060). Like tlie preceding, but witli iiisunken spire. 



Volvaria Lam. Cylindrical, witli involute, concealed spire. Surface usually 

 spirally striated ; aperture narrow ; columella with four anterior plications. Eocene. 

 Ovulacfaeon Dall. Similar in form to Gy2)raea, l)ut without jilications. Recent. 



