786 NORTH AMERICAN INDEX FOSSILS. 



CLXXIX. Typhis Montfort. 

 Like Murex, but the varices are rib-like, the spines are hollow 

 and less regular, and the short anterior canal is completely closed. 

 Cretacic-Recent. 



581. T. curvirostratus Conrad. (Fig. 1 149.) Oligocenic. 

 Spire somewhat lower than the next; sides of whorls more nearly 



straight ; ribs strong and ending in vertical spines ; aperture small 

 and round ; anterior beak strongly curved. 

 Vicksburgian of Mississippi. 



582. T. acuticosta Conrad. (Fig. 11 50, a, b.) Miocenic. 



a 

 Fig. 1 150. a, b. Typhis acnticjsta ; c, d, Trophon tetricus. (Md. Survey.) 



Whorls with four or five varices ending at the shoulder angle 

 in compressed spines, alternating with four shorter, rounded varices 

 ending in hollow spines or tubes. Rostrum slightly reflected. 



Chesapeakean formation of Atlantic coast. 

 583. T. obesus Gabb. Oligocenic-Pliocenic. 



Short and broad with low spire; whorls sharply angulated, con- 

 cave above and convex below suture ; four varices to each whorl, 

 acute-angular on their margins and ending in blunt process on 

 upper angle of whorl ; shell swollen at base of tubular spines ; sur- 

 face polished, with few spirals. 



Chipolan beds of Jamaica and Florida ; Miocenic of Haiti ; Plio- 

 cenic of Trinidad. 



CLXXX. Trophon Montfort. 

 Like the preceding, but the varices are lamellose and the canal 

 open. Tertiary-Recent. 



