HELICIDJE. 181 



7. Bulimus. (Twist Shell.) 



The animal is moderately large (like the snails), 

 with four tentacles, a small elongate foot, and a long- 

 central, slender, spiral body, covered with an ob- 

 long shell ; the spire produced and ending rather 

 acutely, with the ultimate volution larger than the 

 next; aperture oval, entire at the base, without 

 teeth, not half as long as the spire; the peristome 

 interrupted ; outer lip generally thickened, reflexed. 



The shell of this genus is distinguished from that of 

 Limnceus in wanting the oblique fold on the pillar ; 

 from the Clausillce in being regular, and in having 

 the peristome simple and interrupted; and from the 

 Pupcs in having the spire regularly tapering. 



The animal of this genus (and of Pupa according to 

 M. Deshayes) is distinguished from the snail (Helix) 

 in being destitute of any vesicula multifida. 



Probably called Bulimus from their eagerness to 

 feed on vegetable substances. 



Hartmann, and since him Mr. Broderip, have 

 changed the name of this genus to Bulinus, thinking 

 probably that it was derived from the Bulin of Adan- 

 son, but that is an Aplexus. 



They may be divided into two sections. 



a. En a Leach. 



Shell ovate, whorls gradually enlarging, covered with a 

 brown periostraca ; peristome thickened, rejiexed. 



59. 1. Bulimus Lackamensis. Wiltshire Twist Shell, 

 (t. 6. f. 62.) Shell conic-oblong, reddish brown, 

 obliquely striolate ; the peristome reflected and 

 forming an umbilicus. 



