GASTROPODA— FUSIDJE. 



771 



550. F. (Piestrocheilus) culbertsoni M. and H. (Fig. 1126.) 



Cretacic. 



Fusiform spire of length of aperture; whorls round; suture 

 scarcely impressed; surface with rounded, low ribs which become 

 obsolete in adult of many specimens; spirals uniform; from one to 

 four plaits on columella, not visible at aperture. 



Fox Hills of Moreau River, and of Black Hills of Dakota. 



Family Fusion. 



CLX. Fusus Lamarck. 



Spindle-shaped, with spire and canaliculate rostrum of about 



equal length in typical forms; protoconch oblique and smooth in 



early, ribbed in later whorls; abruptly defined from conch which 



Fig. 1 127. a, Fusus haitensis ; b, F. henekeni. (After Guppy, Q. J. G. S., XXXII.) 



begins with round ribbed whorls; later whorls often angular and 

 nodose; body whorl abruptly contracted to canal; lips smooth. 

 Eocenic-Recent. 



