CLASS IV 



GASTROPODA 



541 



Family 4. Capulidae Cuviei'. 



Shell cup-, cap-shaped or oval, irregular, loith spirally twisted apex; in some cases 

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

 operculum absent. Marine. Cambrian to Recent. 



Various genera belonging here are stationary, remaining tlirougliout nearly the 

 whole of their existence attached to some foreign body, to 

 which they gradually become accommodated in form. 



Stenotheca Salter. Shell small, cap-shaped, concentrically 

 striated or furrowed, with slightly incurved apex, which 

 latter is distantly situated posteriorly. Lower Cambrian. 



Fia. 933. 



'Capuhis hungarlcus (Linn.). 

 Pliocene ; Tuscany. ' 



Fig. 934. 



Capulus rugosus (Sowb.). 

 Great Oolite ; " Langrune, 

 Calvados. I'j 



Fig. 935. 



OrtJionychia clcgans Barr. 

 Silurian (Etage E) ; Loclikow, 

 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 irregular ; internally with a horseshoe-shaped muscular 

 impression. Exceedingly abimdant 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. 



Fig. 936. 



Platyceras neritoides Pliil. 

 Carboniferous ; Vise, Belgium. 



Pig. 937. 



Diaplwrostoma 

 Hall. Silurian ; 

 Indiana. 



niagarense 

 Waldron, 



Fig. 93S. 



Horiostmna harrandei Mun.-Clialm. 

 Lower Devonian ; Gahard, lUe-et- 

 Vilaine (after Munier-Chalmas). 



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

 as in Diaphorostoma, late stages non-coiling, often spinous. Commensal on Echinoicls. 

 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 thick, spirally ribbed, with short 

 lateral spire, and wide umbilicus. Devonian. 



Tubina Barr. Silurian. Bothiiletzia Simonelli. Tertiary. 



