7$o 



NORTH AMERICAN INDEX FOSSILS. 



Caloosahatchie beds of Florida. 

 592. M. (Conomitra) staminea Conrad. (Fig. 11 55.) 



Oligocenic-Recent. 



Spire and aperture about equal; whorls rounded; suture moder- 

 ately depressed ; ribs faint ; columella with four plications. 



Vicksburgian of Mississippi; Miocenic of Florida. 



Family Volutim: Gray. 

 CLXXXIV. Volutilithes Swainson. 

 Fusiform or Fulgur-shaLped shells with more or less conical 

 spire ; protoconch of several increasing whorls, acute ; whorls cos- 

 tate ; aperture elongate and with broad but short canal ; columella 

 plicate, more strongly near anterior end. Cretacic-Recent. (A 

 number of subgenera, better perhaps regarded as genera, are in- 

 cluded here.) 

 593. V. petrosus (Conrad). (Fig. 11 56.) Eocenic. 



Fig. 1156. Volutilithes petrosus, opposite views, 

 and young. (Md. Survey.) 



Fig. 1 157. Volutilithes 

 sayana. (After Conrad. ) 



Young shell Fulguroid, whorls embracing to angle which is spi- 

 nose, the spines continued downward as ribs; shoulder changing 

 from round to concave; in adult the whorls are more irregular; 

 last one with strong spines on the angle; callus of inner lip large, 

 covering part of whorl and shoulder; presence of earlier calluses 

 indicated on shoulder of preceding whorls; columella with three 

 plications. 



