Xll BULIMULID^E. 



a 1 . Apical whorls most minutely, evenly cancellate, as in pi. 15, fig. 



31, neither spiral nor vertical sculpture predominating; or in 



other words, with minute pits in spiral and straight vertical series. 



b. Shell strong, the peristome thick, with strong callous flanges 



within lip and columella ; spire short. Otostomus, x, 107. 



ft 1 . Shell elongate, the aperture having teeth, or angular below. 



Odontostomus, xiv, 38. 

 ft 2 . Aperture without teeth or folds ; shell rather thin. 



c. Base obliquely truncate. Zaplagius, xi, 185. 



c l . Base tapering, rarely angular ; lip varying from unex- 

 panded to reflexed. -Drym8eus t xi, 191. 



a 2 . Apical whorls with straight vertical riblets. 

 b. Aperture provided with teeth or folds. 



OdontostomuSi in part, xiv, p. 38. 

 b 1 . Aperture ovate, without teeth. 



c. Intervals between the apical riblets conspicuously 



striate spirally. Neopetraeus, xi, 163. 



c 1 . Intervals smooth or weakly striate spirally. Bulimulus, 



division III, xi, 83; and Bothriembryon, in part, 



xiii, p. 1. 



a 3 . Apical whorls sculptured with waved, irregular or dislocated 

 wrinkles, sometimes forming a net or mesh pattern, or pitted in 

 the pattern of a thimble. 



b. Aperture with several pliciform teeth or folds. 



Odontostomus, in part, xiv, p. 93. 



ft 1 . Aperture with obtuse teeth, or a callus on the parietal wall 

 defining a posterior groove ; whorls 4J to 5J. 



Hyperaulax, xiv, p. 102. 



6 2 . Aperture ovate, without teeth or posterior groove. 

 c: American genera. 



d. Wholly imperforate, large, elaborately variegated, 

 apex'conspicuously thimble-pitted. 



OrthalicuS) xii, 186. 



d l . Usually rimate or umbilicate ; rather large, brown 

 or marked with brown. 



e. Shell dappled or zigzag-streaked. 



Plekocheilus, x, 62. 

 e l . Shell streaked, banded or unicolored. 



Thaumastus, x, 43. 



