Bulletin 24 46 



ed with 9 to 11 raised revolving ribs, separated by as wide or wid- 

 er interspaces ; on the body of the whorl the ribs become more 

 numerous, also finer on the anterior canal ; the suture, bordered 

 by a flattened area which generally carries a single carination ; 

 the revolving lines are additionally crossed by wave-like lines 

 which are parallel to the growth lines and cause the carination of 

 the ribs. 



Height 20, greater diameter 11 mm. {Specimen figured) 



This shell when not full-grown appears perfectly distinct. 

 In its later development the shell does not increase much in height 

 but becomes more globose, like the typical form. It is then dis- 

 tinguished by its more numerous revolving ribs and in having 

 generally the flattened area next to the suture with a carinated 

 line. 



Yorktown formation : Kingsmills, Grove Wharf 



Typhis harrisi, n. sp., Plate 2, Figs. 7, 9 



Shell of moderate size ; whorls polished ; whorls about 5, 

 with 4 large, thick varices, which on the body whorl extend com- 

 pletely across the whorl and onto the anterior canal ; between 

 these are shorter varices which continue only to just below the 

 middle of the whorl ; the varices carry on the shoulder of the 

 whorls a hollow, recurved spine ; these are generally broken off, 

 and represented only by hollow stumps ; whorls above the 

 shoulder are irregularly flattened and with the suture appress- 

 ed ; on this area only the smaller varices continue across 

 to the suture ; surface of shell smooth with only growth lines 

 which extend up onto the spines ; the varix next to the mouth 

 carries about four raised ridges which are placed at right angles 

 to the aperture ; on the body whorl resting marks are indicated 

 by raised lines between the varices and representing the aperture 

 and each of the larger varices have on their summit a wavy line 

 formed by raised ridges corresponding to those at the aperture ; 

 canal broad and flattened, recurved and ending in a hollow stump 

 which probably represents the base of a recurved spine ; aperture 

 round or subovate with a raised rim. 

 Height 20, diameter 13 mm 



