.32 



MOLLUSCA 



THYLUM VI 



Gihbula Eisso (Figs, 885, 886). Turbinate or low conical, iinibilicate, and witli 

 roiinded apertiire. Tertiary and Recent. 



Fig. 887. 



Calliostoma semi- 

 putictatum Münst. 

 Keuper ; St. Cas- 

 sian, Tyrol. 2/^. 



Calliostoma aequalis 

 Buv. Coral-Rag ; St. 

 Mihiel; Meuse. 



Fig. 889. 



Leimsiella conica (d'Orb.). 

 Middle Lias ; May, Cal- 

 vados. 



Fig. 890. 



Solariella peregrina 

 (Libassi). Pliocene ; Or- 

 ciaiio, Tuscaiiy. 



Fig. 891. 



Margaritcs margaritula 

 Mer. Oligocene ; Weinlieim, 

 near Alzey, Baden. 



GalUostoma Swains. {Ziziphinus Gray) (Figs. 887, 888). Conical, with peripheral 

 keel and flattened base. Trias to Recent. 



Otlier genera are Cantharidus Montfort ; Leivisiella 

 Stol. (Fig. 889); Tegula Lesson; Solariella Wood 

 (Fig. 890) ; Margarites Leach (Fig. 891) ; Danilia Brus. 

 (Fig. 892) ; Gamitia Gray, and many others. Most of 

 these liave a more or less extensive Tertiary liistory. 



Family 12. Umtaoniidae Adams. 



Fig. 892. 



Danilia cZaiTiraia (Etall.). Coral-Rag 

 Valfin, Ain. 2/^. 



Shell small, usually depressed discoidal, s7nooth and 

 lustrous, or ivith fine spiral Striae, and without nacreous 

 layer. Outer lip sharp, peristome discontinuous. Um- 

 bilicus often concealed hy a callus ; operculum liorny. Silurian to Recent. 



Allied to the Recent genera Umbonium Link (Rotella Lam.), Tsanda Adams, 



Fig. 893. 



^, , Fig. 894. 



Chrysostoma 



acmon(d'Orh.). Teinostoma rotellae- 



Middle Jura ; formis Desh. Calcaire 



Baiin, near Grossier ; Grignon, 



Cracow. near Paris. 



Helicocryptus pusillus (Roem.). Coral- 

 Rag ; Lindener Berg, near Hannover. 



iFiG. 896. 



Adeorbis tr 

 Desh. Middle 

 (Auversien) ; 

 Seine-et-Oise. 



icostatus 

 Eocene 

 Auvers, 



etc., are a nnmber of fossil forms, such as Pycnomphalus Lindström, from the 

 Silurian and Devonian ; Änomphalus Meek and Worthen, and Rotellina de Koninck, 

 from the Carboniferous ; Ghrysostoma Swainson (Fig. 893), from the Jura, and others, 

 which are probably the ancestors of the Umboniidae. 



Whether the genera Teinostoma (Fig. 894) and Vitrinella Adams, together with 

 their fossil allies from the Carboniferous onward, are rightly assigned to this group, is 

 doubtful. Helicocryptus d'Orb. (Fig. 895), from the Jura and Cretaceous, is similar to 

 Vitrinella. Gyclostrema Marryat, comprising small, lustrous shells, and the spirally 

 Stria ted ones known as Adeorbis S. Woodw. (Fig. 896), present some resemblances to 

 the Umboniidae ; but, according to Fischer, they form separate families. All of these 

 genera have fossil representatives in the Tertiary. 



