CLASS IV 



GASTßOPODA 



541 



Family 4. Oapulidae Cuvier. 



Shell cu2J-f ca])-shai)ed or oval, irregulär^ with spirally twisted apex ; in some cases 

 the shell is comjwsed of several depressed whorls. Body whorl very large ; aperture wide ; 

 operculum absent. Marine. Cambrian to Receiit. 



Various genera beloiiging liere are stationary, remaining througliout nearly the 

 wliole of tlieir existence attached to some foreign body, to 

 wliich tliey gradually become accommodated in form. 



Stenotheca Salter. Shell small, cap-shaped, concentrically 

 striated or fiirrowed, with slightly incurved apex, whicli 

 latter is distantly situated posteriorly. Lower Cambrian. 



Capulus hungaricus (Linii.). 

 Pliocene ; Tuscany. 



Fig. 934. 



Capulus rugosus (Sowb.). 

 Great Oolite ; Langrune, 

 Calvados, i 'i 



Fig. 935. 



OrthonycMa elegans Barr. 

 Silurian (Etage E) ; Lochkow, 

 Bohemia. 



Capulus Montf. (Pileopsis Lam.; Brocchia Bronn) (Figs. 933, 934). Irregularly 

 conical or cap-shaped ; apex greatly displaced backward, more or less spirally inroUed. 

 Aperture wide, rounded or irregulär ; internally with a horseshoe-shaped muscular 

 Impression. Exceedingly abundant from the Cambrian to Carboniferous, but rather 

 sparse from the Trias onward. 



Orthonychia Hall {Igoceras Hall) (Fig. 935). Shell conical, straight or slightly 

 curved, often plicated. Apex but faintly spiral. Silurian to Carboniferous. 



Platyceras Conrad {Acroculia Phil.) (Fig. 936). Apex bent and spirally inroUed. 



Platyceras neritoides Phil. 

 Carboniferous ; Vis6, Belgium, 



Diaphorostoma 

 Hall. Silurian ; 

 Indiana. 



:. 93^. 



Horiostoma harrandci Mun.-Chalm. 

 Lower Devonian ; Gahard, lUe-et- 

 Vilaine (after Munier -Chalmas). 



Surface smooth, striated, plicated or covered with small spines. Young shell coiled 

 as in Diaphorostowa, late stages non-coiling, often spinous. Commensal on Echinoids. 

 Silurian to Coal Measures. 



Diaphorostoma Fisher {Platyostoma Conrad) (Fig. 937). Shell composed of numerous 

 rapidly widening whorls. Spire low, body whorl very large. Inner lip reflected and 

 somewhat thickened. Aperture round, of large size. Silurian to Carboniferous. 



Horiostoma Munier-Chalm. (Fig. 938). Shell ihick, spirally ribbed, with short 

 lateral spire, and wide umbilicus. Devonian. 



Tuhina Barr. Silurian. Rothpletzia Simonelli. Tertiary. 



